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1 of 90 Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Cautions and warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 User interface choices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Related information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Celerra iSCSI architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Characteristics of Celerra iSCSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Celerra iSCSI LUNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 LUN masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 CHAP authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 iSCSI digests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 iSCSI discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Asynchronous event messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Persistent reservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Planning considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Configuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Create an iSCSI target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Create an iSCSI LUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Create an iSCSI LUN mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 (Optional) Configure iSNS on the Data Mover . . . . . . . . . . . . . . . . . 23 (Optional) Configure the ESI port for iSNS . . . . . . . . . . . . . . . . . . . . 24 (Optional) Create a CHAP entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Start the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Managing the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Stop the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Check the status of iSNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Change the iSNS configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Clear iSNS configuration information . . . . . . . . . . . . . . . . . . . . . . . . 30 Configure iSCSI digests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 View digest settings for the iSCSI service . . . . . . . . . . . . . . . . . . . . 32 Control iSCSI discovery responses . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Control asynchronous event messages . . . . . . . . . . . . . . . . . . . . . . 33 Configuring iSCSI Targets on EMC Celerra P/N 300-004-153 Rev A04 Version 5.6.42 February 2009

Configuring iSCSI Targets on EMC Celerra

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Page 1: Configuring iSCSI Targets on EMC Celerra

1 of 90

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Cautions and warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5User interface choices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Related information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Celerra iSCSI architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Characteristics of Celerra iSCSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Celerra iSCSI LUNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11LUN masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14CHAP authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15iSCSI digests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15iSCSI discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Asynchronous event messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Persistent reservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Planning considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Configuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Create an iSCSI target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Create an iSCSI LUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Create an iSCSI LUN mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22(Optional) Configure iSNS on the Data Mover . . . . . . . . . . . . . . . . .23(Optional) Configure the ESI port for iSNS . . . . . . . . . . . . . . . . . . . .24(Optional) Create a CHAP entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Start the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Managing the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Stop the iSCSI service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Check the status of iSNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Change the iSNS configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Clear iSNS configuration information . . . . . . . . . . . . . . . . . . . . . . . .30Configure iSCSI digests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31View digest settings for the iSCSI service . . . . . . . . . . . . . . . . . . . .32Control iSCSI discovery responses . . . . . . . . . . . . . . . . . . . . . . . . . .33Control asynchronous event messages . . . . . . . . . . . . . . . . . . . . . .33

Configuring iSCSI Targets on EMC CelerraP/N 300-004-153

Rev A04

Version 5.6.42February 2009

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Enable or disable APTPL support for persistent reservation . . . . .34Managing iSCSI targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

List iSCSI targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35View iSCSI target properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36View login statistics for an iSCSI target . . . . . . . . . . . . . . . . . . . . . .37Rename an iSCSI target alias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Change network portals for an iSCSI target . . . . . . . . . . . . . . . . . . .39Delete an iSCSI target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Managing iSCSI LUNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41List iSCSI LUNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41View iSCSI LUN properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42Change an iSCSI LUN to read-only . . . . . . . . . . . . . . . . . . . . . . . . . .43Change an iSCSI LUN to read/write . . . . . . . . . . . . . . . . . . . . . . . . . .44View read/write statistics for an iSCSI LUN . . . . . . . . . . . . . . . . . . .45Extend an iSCSI LUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46Update a Windows host after extending an iSCSI LUN . . . . . . . . . .47Update a Linux host after extending an iSCSI LUN . . . . . . . . . . . . .48Delete an iSCSI LUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Configure the maximum number of LUNs per target . . . . . . . . . . . .50

Managing iSCSI LUN masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51List iSCSI LUN masks for a target . . . . . . . . . . . . . . . . . . . . . . . . . . .51Change grants for an iSCSI LUN mask . . . . . . . . . . . . . . . . . . . . . . .52Delete an iSCSI LUN mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Managing CHAP authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54Enforce CHAP authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54View CHAP entries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55Change a CHAP secret . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56Delete a CHAP entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Managing snapshots of iSCSI LUNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58List snapshots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58View information about a snapshot . . . . . . . . . . . . . . . . . . . . . . . . . .59Create a snapshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60Modify the application data associated with a snapshot . . . . . . . . .61Delete a snapshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62Restore a production LUN from a snapshot . . . . . . . . . . . . . . . . . . .63Promote a snapshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64Demote a snapshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Where to get help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66EMC E-Lab Interoperability Navigator . . . . . . . . . . . . . . . . . . . . . . . .66Troubleshooting checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Error messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68Customer training programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Appendix: Understanding iSCSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74iSCSI protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75iSCSI network topologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76iSCSI components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77iSCSI naming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81iSCSI discovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83iSCSI authentication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

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IntroductionThis document is part of the EMC® Celerra® Network Server information set and is intended for system administrators who plan to store data on iSCSI logical units (LUNs) provided by a Celerra Network Server.

iSCSI (Internet Small Computer Systems Interface) is a transport protocol for sending SCSI packets over TCP/IP networks. iSCSI initiators and targets are the key components in an iSCSI architecture. Initiators and targets are devices (software or hardware) that package and transfer SCSI information over an IP network. An iSCSI initiator encapsulates SCSI commands, data, and status information in iSCSI packets and sends the packets to an iSCSI target that resides on a storage device. "Appendix: Understanding iSCSI" on page 74 provides more information about the iSCSI protocol.

This document describes how to configure and manage iSCSI targets and LUNs on a Celerra Network Server.

For information about configuring iSCSI initiators on a host system, consult the documentation for the host system and for the iSCSI initiator software or hardware.

System requirementsTable 1 on page 3 lists the software, hardware, network, and storage configurations.

Table 1 System requirements

Software Celerra Network Server version 5.6 or later.Celerra Network Server version 5.6.39 or later for persistent reservation support.

Hardware No specific hardware requirements.

Network An Ethernet 10/100/1000 network with:• (Windows) One or more iSCSI hosts configured with the most recent version

of the Microsoft iSCSI Software Initiator. • (Optional) A Microsoft iSNS server.

Storage No specific storage requirements.

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RestrictionsThese restrictions and limitations apply:

◆ Celerra iSCSI does not support the Microsoft iSCSI Initiator running on a Microsoft Windows XP host.

◆ iSCSI LUNs are not supported by Celerra Virtual Data Movers (VDMs).

◆ EMC SnapSure™ checkpoints are not supported on iSCSI file systems.

◆ EMC Celerra Replicator™ (V1) is not supported on iSCSI file systems. Instead, use Celerra Replicator for iSCSI (V1) or Celerra Replicator (V2) to perform replication and failover for iSCSI LUNs.

◆ When using a virtually provisioned iSCSI LUN, monitoring file system space is crucial to ensure that enough space is available.

!CAUTION!Insufficient space on a file system that contains a virtually provisioned LUN results in data unavailability and might cause data loss. In addition to monitoring file system usage, set an event notification for a file system full condition and enable automatic file system extension with a conservative threshold. If enough disk space is not available for file system extension, data loss might still occur.

◆ With Celerra Manager, you can create only regular iSCSI LUNs. To create a virtually provisioned iSCSI LUN, you must use the CLI.

◆ The automatic file system extension option supports virtually provisioned iSCSI LUNs, but not regular iSCSI LUNs. You cannot create a regular iSCSI LUN on a file system enabled for automatic extension. You also cannot enable automatic file system extension if a regular iSCSI LUN is present.

◆ To successfully extend an iSCSI LUN through the Windows diskpart utility, the LUN must be a minimum of 128 MB and the extension size must be at least 8 MB. Before extending the LUN, rescan the disk by using diskpart or Disk Management. On Microsoft Windows 2000 systems, log out from the iSCSI initiator, and then log in again to enable the host to discover the changed LUN size.

◆ FileMover and MPFS are not supported on Celerra iSCSI LUNs.

◆ Celerra AntiVirus Agent (CAVA) is not supported on Celerra iSCSI LUNs. Use an antivirus utility on the iSCSI host to scan a mounted Celerra iSCSI LUN.

◆ The Celerra iSCSI feature supports native iSCSI topologies only, not bridging, as described in "iSCSI network topologies" on page 76.

◆ IP security protocol (IPSec) is not supported.

◆ The Celerra iSCSI target supports Microsoft Cluster Server (MSCS) under the Microsoft interim support policy. The iSCSI Cluster Support Frequently Asked Questions in the Microsoft Window Server 2003 web pages at the Microsoft website provide information about this policy.

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◆ If you have a regular LUN on a file system, but have not yet written any data to the LUN, the server_df command reports free disk space as if the LUN is full.

◆ The server_df command shows used and available space as determined by the server. You cannot use this command to determine available space from the viewpoint of the iSCSI initiator or host applications. For example, deleting files on the client side does not necessarily increase the amount of available space shown by the server_df command.

◆ The server_iscsi command can show zero allocated space (alloc=0MB) for a production LUN (PLU) and for a promoted snapshot (TWS). The PLU and the TWS share the used blocks with the snapshot, which is the owner of the allocated blocks.

◆ When using 64-bit SUSE Linux 9, the software iSCSI initiator sometimes cannot discover the LUN of a snapshot promoted through the server_iscsi command. Ensure that the target provides a LUN mask that allows the initiator to access the promoted snapshot LUN. If the client still cannot discover the LUN, type this command on the Linux host:

/etc/init.d/iscsi reload

The Microsoft iSCSI Initiator imposes these additional restrictions:

◆ Multiple connections per session are supported on Windows platforms with Microsoft iSCSI Software Initiator 2.0.

◆ Windows dynamic disks are not supported.

Cautions and warningsIf the following information is unclear, contact your EMC Customer Support Representative for assistance:

◆ Do not run the nas_fsck command on file systems with iSCSI LUNs unless necessary. If you do, log out all iSCSI initiators connected to the LUNs. Failure to disconnect all iSCSI initiators before running the command can result in data loss.

◆ Remounting an iSCSI file system is normally prevented, but can be forced by using the -Force option with the server_mount command. An iSCSI file system should not be remounted unless necessary. If you do, log out all iSCSI initiators connected to LUNs on the file system. Failure to disconnect all iSCSI initiators before remounting the file system can result in data loss.

◆ Snapshots of iSCSI LUNs are not intended for use as mirrors, disaster recovery, or high-availability tools. Because iSCSI snapshots are partially derived from real-time data on iSCSI LUNs, snapshots can become inaccessible (not readable) if the production LUNs become inaccessible. Only snapshots saved to an alternative storage location can be used to provide disaster recovery.

◆ Do not stop the iSCSI service if an iSCSI initiator is connected to any target on the Data Mover. Doing so could cause the systems that host the iSCSI initiators to stop responding.

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◆ Unless you are using Celerra iSCSI targets in a clustered environment, do not grant multiple initiators access to the same LUN. Conflicts can occur if more than one initiator tries to write to the LUN. If the LUN is formatted with the NTFS file system in Windows, simultaneous writes can corrupt the NTFS file system. Avoid granting an initiator access to a LUN that is not yet defined.

◆ Changes to LUN masks take effect immediately. Be careful when deleting or modifying a LUN mask for an initiator with an active session. If the initiator loses access to LUNs in use, applications that are using those LUNs are affected.

◆ Data written to a promoted iSCSI LUN is lost when that LUN is demoted.

◆ Closely monitor file system space that contains virtually provisioned iSCSI LUNs. You can use the CLI commands server_df and nas_fs -size or Celerra Manager to determine used or available space in a file system. To avoid exceeding the available file system space and possible data loss when using such iSCSI LUNs, enable automatic file system extension with a conservative threshold. If enough disk space is not available for file extension, data loss might still occur.

◆ When using a high water mark (HWM) for automatic file system extension, the number of used blocks determines when the HWM is reached. File system extension can occur even when usage of the production LUN appears to be low from the host’s perspective. Snapshots, for example, consume additional file system space. Also, deleting data from a LUN does not reduce the number of blocks allocated to the LUN.

◆ On Linux systems with the Cisco initiator, use caution when formatting a file system on a virtually provisioned LUN. Ensure that enough space is available on the file system. A file system that is too small can cause the Linux host to stop responding. Set the high water mark to 90 percent or less.

◆ Do not use file systems with iSCSI LUNs for other purposes. For example, do not export an iSCSI file system through a CIFS share or NFS export. Although a CIFS or NFS client can see the LUN as a file in the file system and copy the LUN, the CIFS and NFS protocols cannot understand its contents.

◆ Avoid deleting the most recent snapshot of a production LUN while I/O is active. I/O timeout problems can occur if the latest snapshot is very large, possibly resulting in data corruption. As a workaround, create a new snapshot and then delete the previous one.

◆ Do not create a LUN mask for a read-only iSCSI LUN, or try to read or verify the contents of a read-only destination LUN.

◆ A bug in Celerra Network Server version 5.5 causes the VMWare ESX Server to use the wrong method for constructing device IDs for Celerra iSCSI LUNs. Version 5.6 corrects this problem. If you upgrade from version 5.5 to 5.6, the ESX Server misinterprets the older, mismatched device IDs and might see those disks as snapshot LUNs. To correct this problem, you must perform a resignature to generate proper device IDs for the Celerra iSCSI LUNs. Primus article emc189395 provides detailed information.

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User interface choicesThe Celerra Network Server offers flexibility in managing networked storage that is based on your support environment and interface preferences. This document describes how to configure Celerra iSCSI by using the Celerra command line interface (CLI). You can also perform most of these tasks by using Celerra Manager.

Table 2 on page 7 summarizes the attributes of each interface.

The EMC Celerra Network Server Release Notes provide additional, late-breaking information about Celerra management applications.

These documents provide additional information about managing a Celerra system:

◆ The topic, Learning about EMC Celerra, on the EMC Celerra Network Server Documentation CD

◆ Celerra Manager online help

Installing EMC Celerra Management Applications includes instructions for starting Celerra Manager.

TerminologyThe EMC Celerra Glossary provides a complete list of Celerra terminology.

Challenge Handshake Authentication Protocol (CHAP): Access control protocol for secure authentication using shared passwords called secrets.

command descriptor block (CDB): SCSI term for a fixed block of data transmitted as a single entity. A CDB is a SCSI packet.

demote: To unmount a snapshot from an iSCSI LUN. Upon demotion, the LUN is inaccessible and changes made to the LUN while in a promoted state are lost.

Table 2 Interface options

Interface Behavior Reference

Celerra CLI The Celerra command line interface provides the most comprehensive iSCSI management functions. This document refers to these CLI commands:• nas_fs• nas_fsck• server_df• server_iscsi• server_param• server_security

Online Celerra man pages or EMC Celerra Network Server Command Reference Manual

Celerra Manager

Celerra Manager limitations:• Cannot list login statistics for iSCSI targets or read/write

statistics for iSCSI LUNs.• Cannot create a virtually provisioned iSCSI LUN.• Cannot create or manage snapshots of iSCSI LUNs.

Celerra Manager online help

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digest: iSCSI protocol error-checking method used to verify the integrity of an iSCSI packet header (header digest) or payload data (data digest) using a checksum.

extended unique identifier (EUI): IEEE naming standard supported by the iSCSI protocol. The format of EUI names is eui. followed by an EUI-64 identifier.

file storage object: File created on a UxFS file system that provides the storage space for an iSCSI LUN.

Internet SCSI (iSCSI): Protocol for sending SCSI packets over TCP/IP networks.

Internet Storage Name Service (iSNS): Discovery and naming protocol designed to facilitate the automated discovery, management, and configuration of iSCSI and Fibre Channel Protocol (FCP) devices on a TCP/IP network.

iSCSI host: Computer hosting an iSCSI initiator.

iSCSI initiator: iSCSI endpoint, identified by a unique iSCSI name, which begins an iSCSI session by issuing a command to the other endpoint (the target).

iSCSI qualified name (IQN): Naming standard supported by the iSCSI protocol. IQN names are globally unique and in the form of iqn. followed by a date and a reversed domain name.

iSCSI target: iSCSI endpoint, identified by a unique iSCSI name, which executes commands issued by the iSCSI initiator.

logical unit (LU): For iSCSI on a Celerra Network Server, a logical unit is an iSCSI software feature that processes SCSI commands, such as reading from and writing to storage media. From an iSCSI host perspective, a logical unit appears as a disk device.

logical unit number (LUN): Identifying number of a SCSI or iSCSI object that processes SCSI commands. The LUN is the last part of the SCSI address for a SCSI object. The LUN is an ID for the logical unit, but the term is often used to refer to the logical unit itself.

LUN mask: Set of access permissions that identify which iSCSI initiator can access specific LUNs on a target.

network portal: Component that listens for and is capable of accepting iSCSI connections within a given iSCSI session. A network portal for an iSCSI initiator is identified by its IP address. A network portal for an iSCSI target is identified by its IP address, listening TCP port, and group tag.

Persistent Block Reservation (PBR): Technique of reserving an adequate number of blocks in a file system to support creation of a logical unit of a specified size. The blocks are reserved for the logical unit whether or not in use.

portal group: Collection of network portals for a given iSCSI target.

production logical unit (PLU): iSCSI LUN that serves as a primary storage device. A PLU can be configured as a disk device through an iSCSI initiator.

promote: To mount a snapshot to an iSCSI LUN so it can be configured as a disk device through an iSCSI initiator.

Protocol Data Unit (PDU): iSCSI term for a fixed block of data transmitted as a single entity. A PDU is an iSCSI packet.

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regular iSCSI LUN: iSCSI LUN that uses Persistent Block Reservation (PBR) to ensure that the file system has sufficient space for all data that might be written to the LUN.

small computer system interface (SCSI): Standard set of protocols for host computers communicating with attached peripherals.

snapshot: Generic term for a point-in-time copy of data.

snapshot logical unit (SLU): Snapshot promoted to logical unit status and configurable as a disk device through an iSCSI initiator.

virtually provisioned iSCSI LUN: iSCSI LUN without reserved space on the file system. Adequate file system space must be available for allocation whenever data is added to the LUN.

Volume Shadow Copy Service (VSS) : Windows service and architecture that coordinates various components to create consistent point-in-time copies of data called shadow copies.

Related informationThese Celerra documents provide information beyond the scope of this document:

◆ iSCSI SnapSure Manager for Exchange 2000 Help

◆ Using EMC Celerra Replicator for iSCSI (V1)

◆ Using EMC Celerra Replicator (V2)

◆ EMC Celerra Network Server Command Reference Manual

◆ Online Celerra man pages

◆ EMC Celerra Network Server Parameters Guide

◆ Managing EMC Celerra Volumes and File Systems Manually

◆ Managing EMC Celerra Volumes and File Systems with Automatic Volume Management

◆ Configuring EMC Celerra Events and Notifications

◆ Configuring and Managing EMC Celerra Networking

The EMC Celerra Network Server Documentation CD, supplied with the server and also available on Powerlink®, provides the complete set of Celerra customer publications. After logging in to Powerlink, go to Support > Technical Documentation and Advisories > Hardware/Platforms Documentation > Celerra Network Server. On this page, click Add to Favorites. The Favorites section on your Powerlink home page provides a link that takes you directly to this page.

Other related EMC publications, which are available on Powerlink, include:

◆ EMC Replication Manager Product Guide

◆ EMC Host Connectivity Guide for Windows

In addition, check Powerlink for white papers and other articles on topics related to Celerra iSCSI features.

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ConceptsThe Celerra iSCSI target feature creates a file within a file system on the server and makes it appear to clients as a local SCSI disk. By using Celerra iSCSI LUNs in place of locally attached SCSI disks, you can centralize storage and simplify its management.

Celerra iSCSI architectureCelerra iSCSI is instituted on individual Data Movers and must be configured on each Data Mover. The Data Mover serves as the storage resource in a distributed iSCSI network. The iSCSI service runs independently on each Data Mover. Similarly, the Internet Storage Name Service (iSNS) client, iSCSI targets, and iSCSI LUNs must be configured for each Data Mover.

Figure 1 on page 10 illustrates how the iSCSI, iSNS, and CHAP protocols connect the elements in a Celerra iSCSI network.

Figure 1 iSCSI components and related protocols

EMC provides iSCSI host components, which are services and applications that run on an iSCSI host and operate with iSCSI targets on a Celerra Network Server. iSCSI SnapSure Manager for Exchange 2000 Help describes these components.

iSNSServer

iSNSClient

iSCSITarget

iSCSILUN

StorageObject

iSCSIInitiator

iSCSI Host

CHAPDB

CHAP

iSNS

iSNS

iSCSI SCSI

Data Mover

iSCSI InitiatorClient

iSCSI Target Host(Data Mover)

CNS-000433

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Characteristics of Celerra iSCSICelerra iSCSI support includes:

◆ iSCSI solution is entirely software-based, and requires no iSCSI host bus adapters (HBAs) or iSCSI bridges.

◆ iSCSI configuration persists across Data Mover reboots.

◆ These iSCSI features are supported:

• iSCSI error recovery level 0 (session-level recovery)

• iSCSI digests, ImmediateData, and FirstBurst

◆ CHAP is supported with unlimited entries for one-way authentication or one entry for reverse authentication.

◆ iSNS is used for discovery.

Celerra iSCSI LUNsA logical unit (LUN) is an element on a storage device that interprets SCSI CDBs and runs SCSI commands, such as reading from or writing to storage. As opposed to raw storage array SCSI-device-based LUNs, a Celerra iSCSI LUN is a software feature that processes SCSI commands.

On the iSCSI host system, the LUN appears as a local disk that contains individual files. iSCSI initiators log in to the LUN itself and cannot view other content on the file system—an initiator can see only the files stored on the iSCSI LUN.

An iSCSI LUN is created within a standard Celerra file system and emulates a SCSI disk device by using a dedicated file called a file storage object. The file storage object provides the physical storage space for data stored on the iSCSI LUN.

When creating an iSCSI LUN, you can choose one of two storage methods:

◆ A regular LUN (default) utilizes Persistent Block Reservation (PBR) to ensure the file system has sufficient space for all data that might be written to the LUN. PBR reserves disk space for the entire LUN although the disk space is not taken from the reservation pool (allocated) until data is actually written to the LUN.

◆ A virtually provisioned LUN does not reserve space on the file system. To avoid data loss or corruption, file system space must be available for allocation when data is added to the LUN.

Do not create regular and virtually provisioned LUNs within the same file system.

The automatic file system extension option supports virtually provisioned iSCSI LUNs only. You cannot create a regular iSCSI LUN on a file system enabled for automatic extension. You cannot enable automatic file system extension if a regular iSCSI LUN is present.

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!CAUTION!Insufficient space on a file system that contains a virtually provisioned LUN results in data unavailability and might cause data loss. In addition to monitoring file system usage, set an event notification for file system full condition and enable automatic file system extension with a conservative threshold. If enough disk space is not available for file extension, data loss might still occur.

Configuring EMC Celerra Events and Notifications gives instructions for generating an SNMP trap that issues an email notification when file system usage exceeds a selected threshold.

Managing EMC Celerra Volumes and File Systems with Automatic Volume Management provides information about automatic file system extension.

Extending a LUN does not cause automatic extension of the underlying file system. To ensure that enough space is available for LUN extension, you might need to extend the file system first.

In this document, references to targets and LUNs are iSCSI-specific and not related to SCSI targets and LUNs described in Configuring NDMP Backups on EMC Celerra.

Classes of Celerra iSCSI LUNsCelerra supports two classes of iSCSI LUNs:

◆ Production LUN (PLU): LUN serving as a primary (or production) storage device.

◆ Snapshot LUN (SLU): Point-in-time representation of a PLU promoted to LUN status, allowing it to be accessed.

SnapshotsA snapshot is a point-in-time representation of the data stored on an iSCSI LUN. The initial snapshot requires the same amount of storage as the data that has been written to the LUN. Each subsequent snapshot requires storage only for the changed data. Snapshots can be created either by a host application (such as the CBMCLI commands on a Linux host or Replication Manager on a Windows host) or on the Control Station.

When created, each snapshot is given a globally unique name. The name includes the LUN number. For example, this name indicates that the snapshot is of LUN 24:

fs14_T8_LUN24_000183500235_0006.ckpt009

Note: The characters that precede the LUN number in the snapshot name are generated internally and are unrelated to the user-assigned file system name and iSCSI target alias.

The snapshot also includes an application label, which identifies the application used to create the snapshot. Snapshots created through the Control Station are assigned the application label “CelerraCS.”

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The snapshot can optionally include as many as 4096 bytes of application data. The application data is typically used as comment text to describe the snapshot, but it can also include binary data.

Each snapshot creates a copy of the PLU. The currently allocated (modified) blocks in the PLU are transferred to the snapshot, which becomes the owner of those blocks. The PLU shares the allocated blocks with the snapshot. Subsequent snapshots of the PLU repeat the process. The latest snapshot takes ownership of blocks written (allocated) to the PLU since the previous snapshot, and also shares the allocated blocks owned by previous snapshots.

Unless promoted, a snapshot is not visible to the iSCSI initiator. The promotion operation creates a temporary writable snapshot (TWS) and mounts it to an iSCSI LUN so it can be configured as a disk device and used as a production LUN. The TWS also shares the allocated blocks owned by the promoted snapshot. A snapshot can be promoted only once (that is, you cannot promote an already promoted snapshot). After a snapshot is demoted, it can be promoted again.

Typical uses of the promoted snapshot are to restore damaged or lost data by using the data on the SLU or to provide an alternative data source. Do not use snapshots for backup because a snapshot is only crash-consistent (as if after a power failure) and cannot guarantee application-consistent data.

Although a promoted snapshot LUN is writable, any changes made to the LUN are allocated to the TWS alone. When the snapshot is demoted, the LUN is unmounted and its LUN number is unassigned. Any data written to the promoted LUN is lost and irretrievable.

A production LUN can also be restored from a snapshot. This operation performs a fast (destructive) restore, which deletes all newer snapshots.

Sizing LUNsLUNs require a minimum size of 3 MB and cannot exceed 2 TB minus 1 MB (2,097,151 MB). When you create a LUN, the space taken from the file system is slightly larger than the size you specify for the LUN. This is attributable to overhead in allocating and tracking the LUN by the underlying file system.

LUN numberingEach LUN is identified by a unique number per target. The iSCSI protocol allows a target to have a maximum of 256 LUNs (numbered 0 to 255). The usable range of LUNs, however, might be limited by the operating system of the iSCSI host.

For example, Windows limits the total number of LUNs per target to 255. By default, the server enforces the Windows limitation. For initiators on non-Windows hosts, you can disable Windows-compatible mode to allow 256 LUNs per target. "Configure the maximum number of LUNs per target" on page 50 explains how to disable Windows-compatible mode.

When you create a production LUN, use a number in the range 0 through 127. The server uses the remaining LUN numbers (128 and greater) to mount promoted iSCSI snapshots as LUNs.

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LUN extensionYou can extend the size of an existing iSCSI LUN. After extending a LUN, you must run the appropriate utilities on the iSCSI host system to expand the host volume on the extended LUN. For details, refer to these topics:

◆ "Update a Windows host after extending an iSCSI LUN" on page 47

◆ "Update a Linux host after extending an iSCSI LUN" on page 48

These constraints apply to LUN extension:

◆ Only iSCSI production LUNs (PLUs) can be extended. You cannot extend iSCSI snapshots temporarily mounted as iSCSI LUNs (SLUs).

◆ In an iSCSI replication relationship, only the source LUN can be extended manually. After the source LUN is extended, the destination LUN is extended during the next replication session.

◆ The minimum extension size is 8 MB.

◆ Because of a volume formatting limitation on Windows platforms, the total LUN size after extension must be greater than 129 MB.

◆ Linux systems require adequate space before extending a LUN.

◆ The size of a snapshot does not change if the iSCSI LUN is subsequently extended. Because the snapshot and extended LUN are different sizes, you cannot restore the LUN from the snapshot. You can, however, promote the snapshot and copy data from it.

◆ If automatic file system extension is enabled, extending an iSCSI LUN does not trigger automatic extension of the file system. You might need to extend the underlying file system before you can extend the LUN.

LUN masksA LUN mask, which is defined on a target, specifies an iSCSI initiator and the LUNs to which it has access. In other words, an initiator can access a LUN only if the target explicitly associates the initiator’s formal iSCSI name with the LUN number.

When created, an iSCSI target has no LUN masks, which means no initiator can access any LUN on that target. To enable an initiator to access LUNs on a target, you need to create a LUN mask to specify the initiator and the LUNs it can access.

When defining a LUN mask that grants an initiator access to multiple LUNs on the target, it might be easier in some cases to grant access to a range of LUNs and then deny access to specific LUNs within that range.

For example, suppose you want to allow an initiator access to all LUNs in the range 0 through 12, except for LUNs 6 and 8. In the CLI, you can create a LUN mask by using the -grant option that specifies LUNs 0 through 12, and then modify the mask with the -deny option, specifying LUNs 6 and 8.

Because LUN numbers 128 and greater are used for snapshot LUNs, you should not grant initiators blanket access to LUNs in this range. If you do, “phantom” disks might appear and disappear in the iSCSI host’s device manager as the temporary writable snaps are promoted and demoted.

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!CAUTION!Unless you are using Celerra iSCSI targets in a clustered environment, do not grant two initiators access to the same LUN. Conflicts can occur if more than one initiator tries writing to the LUN. If the LUN is formatted with the NTFS file system in Windows, simultaneous writes might corrupt the NTFS file system on the LUN. As a best practice, do not grant an initiator access to a LUN number if that LUN does not yet exist.

CHAP authenticationBy default, targets on a Data Mover do not require CHAP authentication. Depending on your organization’s needs, you might want to enforce CHAP authentication.

You can enforce CHAP authentication at two different points of the iSCSI login:

◆ Before the initiator logs in to the iSCSI service and establishes an iSCSI discovery session

◆ Before the initiator logs in to the target and establishes a regular iSCSI session

If you use iSNS, discovery is unnecessary. The iSNS service provides the identity of all iSCSI nodes in the network.

If you want a Data Mover to authenticate the identity of each iSCSI initiator, configure CHAP authentication on the Data Mover. To configure CHAP, you must:

◆ Set the appropriate server parameters so that targets on the Data Mover require CHAP authentication. "Enforce CHAP authentication" on page 54 provides instructions for setting the appropriate server parameters.

◆ Create a CHAP entry for each initiator that contacts the Data Mover. CHAP entries are configured on each Data Mover—each initiator has a unique CHAP secret for the Data Mover.

◆ An initiator can be configured to authenticate the identity of the targets as well. In this case, you must configure a CHAP entry for reverse authentication. Reverse authentication entries differ from regular CHAP entries because each Data Mover can have only one CHAP secret for reverse authentication. In other words, the Data Mover uses the same CHAP secret for all iSCSI initiators that require authentication of the target.

iSCSI digestsThe iSCSI protocol supports the inclusion of header and data digests in iSCSI Protocol Data Units (PDUs). Header digests provide cyclic redundancy check (CRC) error checking for PDU header segments. Data digests provide CRC error checking for data segments.

The header and data digest settings on the iSCSI target do not necessarily have to match the settings on the iSCSI initiator, but they must be compatible. When logging in to the target, the initiator checks the digest settings on the target to determine whether they are acceptable based on policies established on the host

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side. For example, if the initiator requires data digests, but the target has disabled data digests, the initiator might refuse to log in.

On the Celerra Network Server, header digests are enabled (preferred) and data digests are disabled (not preferred) by default. You can change the default settings for header and data digests by setting server parameters as described in "Configure iSCSI digests" on page 31.

iSCSI discoveryWhen using SendTargets discovery and not iSNS, the initiator queries the iSCSI service for the names and addresses of all targets on the Data Mover. By default, the service returns information about all targets.

Without appropriate LUN masking, the initiator might not have access to any LUNs on a discovered target. You can filter out inaccessible targets during discovery by setting a server parameter as described in "Control iSCSI discovery responses" on page 33. Discovery then returns information only for targets with LUN masks that grant the initiator access to one or more LUNs.

Asynchronous event messagesBy default, Celerra iSCSI targets send an asynchronous event message to connected iSCSI initiators whenever a LUN is added or removed. If the iSCSI initiator does not support asynchronous event messages, you can disable them by setting a server parameter as described in "Control asynchronous event messages" on page 33. When asynchronous event messages are disabled, the target sends an asynchronous logout message instead.

Persistent reservationCelerra iSCSI supports persistent reservation (PR) for iSCSI LUNs in a cluster environment. Cluster management subsystems, such as Microsoft Windows Server 2008, use SCSI persistent reservation commands to define exclusive or restricted access to iSCSI LUNs for client nodes in a shared disk environment. Reservations persist across initiator-target session failures and recovery actions.

By setting the APTPL (Activate Persist Through Power Loss) bit in the PR command, a cluster can request the server to maintain a copy of the PR registration and reservation information on nonvolatile storage in case of power loss. By default, support of APTPL is disabled on the Celerra Network Server. To support APTPL requests from a cluster, you can adjust a server parameter as described in "Enable or disable APTPL support for persistent reservation" on page 34. This setting applies to all iSCSI targets on the Data Mover.

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Planning considerationsThese topics help you estimate size requirements for iSCSI LUNs and provide guidelines for configuring iSCSI on the server.

Creating and mounting file systems for iSCSI LUNsThe server must have one or more file systems to be used as a dedicated storage resource for the iSCSI LUNs.

You can create and mount a file system through the CLI or Celerra Manager. Managing EMC Celerra Volumes and File Systems Manually and Celerra Manager online help provide instructions.

The minimum size for an iSCSI LUN is 3 MB, and the LUN requires approximately 1 MB for overhead. The file system also requires a small amount of space for overhead. Therefore, the minimum size for a file system that can accommodate an iSCSI LUN is approximately 5 MB to 6 MB.

Estimating size requirements for the file systemAll Celerra iSCSI objects are stored in a parent file system. This file system must be large enough to hold the:

◆ Primary LUN or LUNs

◆ Snapshots for the LUNs

◆ Promoted temporarily writeable snapshots

Sizing Considerations for iSCSI Replication on EMC Celerra provides a complete discussion of the topic.

GuidelinesThese general guidelines apply when configuring iSCSI.

Network

Use iSCSI in a LAN environment and, if possible, on a local subnet to achieve the best performance. To achieve maximum throughput, use a private network. When selecting the network, consider network throughput. The Microsoft website provides recommendations for Microsoft Exchange requirements with iSCSI.

File system

◆ A file system with iSCSI LUNs should be dedicated to iSCSI and not used for other purposes. For example, an iSCSI file system should not be exported through a CIFS share or NFS export.

◆ All space on the file system should be available to iSCSI because, in addition to the space taken by LUNs, snapshots of the LUNs require space. "Estimating size requirements for the file system" on page 17 explains how to calculate the recommended size for file systems.

◆ You must routinely monitor the amount of free space on the iSCSI file system. Without enough free space, you cannot take or promote snapshots. Monitoring file system usage is crucial when using virtually provisioned LUNs. To help in

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monitoring the space usage, you can set a high water mark or warning alert condition.

◆ Because the file system extension process can be time-consuming, set the high water mark conservatively so that space is not exhausted before the extension is complete.

Backup

◆ Take snapshots of iSCSI LUNs at appropriate intervals and copy the snapshots to an alternative storage location. By themselves, iSCSI snapshots do not provide a disaster recovery solution.

◆ Celerra iSCSI does not support Network Data Management Protocol (NDMP) backups. To back up the contents of a Celerra iSCSI LUN, you can:

• For Windows Server 2003: Use a Windows host-side backup utility, such as a VSS-compliant backup application, to copy data from the iSCSI LUN. iSCSI SnapSure Manager for Exchange 2000 Help provides more information about VSS backups.

• For Windows 2000 Server: Take an iSCSI snapshot of the LUN, promote the snapshot, and use a host-side backup application to copy data from the promoted snapshot to alternative storage.

• Use the server_iscsi command to create a snapshot of the iSCSI LUN.

Targets

◆ When creating a target, let the server generate a legal iSCSI name rather than typing a name yourself.

◆ When creating a target, the alias name for the target must be unique on the Data Mover because the alias name is the key field in the server’s iSCSI databases. Alias names are case-sensitive (so targets t1 and T1 can coexist on the same Data Mover).

LUNs

Use LUN numbers in the range 0 through 127 for PLUs. Doing so leaves the remaining (higher numbered) LUN numbers available for mounting iSCSI snapshots by the Celerra iSCSI host applications.

LUN masking

◆ Unless you are using Celerra iSCSI targets in a clustered environment, do not grant two initiators access to the same LUN. Granting multiple initiators access to the same LUN can cause conflicts when more than one initiator tries writing to the LUN. If the LUN is formatted with the NTFS file system in Windows, simultaneous writes can corrupt the NTFS file system on the LUN.

◆ Avoid granting access to LUNs 128 through 254. When you take an iSCSI snapshot, the snapshot is temporarily mounted on a LUN in the range 128 through 254 for verification. If you grant initiator access to these LUNs through LUN masking, phantom disks might appear and disappear in the iSCSI host’s device manager.

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◆ Do not change the LUN mask for a promoted snapshot. When you promote a snapshot through one of the Celerra iSCSI host applications, the snapshot’s LUN is added to the LUN mask for the initiator. If you change a LUN mask for a promoted snapshot, the snapshot is no longer accessible. Promoted snapshots typically use LUN numbers greater than 127.

iSCSI service

◆ Do not stop the iSCSI service if an iSCSI initiator is connected to any target on the Data Mover. Doing so could cause the system that hosts the iSCSI initiator to stop responding.

◆ The server supports data digests but disables them by default because they generate significant CPU overhead. Unless your environment requires them, do not enable data digests.

Microsoft Multipath I/O

If using Multipath I/O (MPIO) with Windows Server 2008, you must enable the MPIO feature and register the Celerra iSCSI devices as MPIO devices:

◆ To enable MPIO, select Server Manager > Features > Add Feature. If prompted, reboot the host.

◆ To register Celerra iSCSI devices as MPIO devices, open the Control Panel, double-click MPIO, and then add the following entry to the MPIO device list, with exactly five spaces between EMC and Celerra:

EMC Celerra

Reboot the host when prompted.

This requirement is for Windows Server 2008. In Windows Server 2003, all devices are enabled for MPIO by default.

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ConfiguringThe configuration tasks are:

◆ "Create an iSCSI target" on page 20

◆ "Create an iSCSI LUN" on page 21

◆ "Create an iSCSI LUN mask" on page 22

◆ "(Optional) Configure iSNS on the Data Mover" on page 23

◆ "(Optional) Configure the ESI port for iSNS" on page 24

◆ "(Optional) Create a CHAP entry" on page 25

◆ "Start the iSCSI service" on page 26

Create an iSCSI targetYou need to create one or more iSCSI targets on a Data Mover so an iSCSI initiator can establish a session with the target.

Action

To create an iSCSI target, use this command syntax:$ server_iscsi <movername> -target -alias <alias_name> -create [<pg_tag>:np=<np_list> [<pg_tag>:np=<np_list> … ]]

where:<movername> = Data Mover on which to create the target.<alias_name> = alias for the target’s formal iSCSI name. The alias is an alphanumeric string of as many as 255 ASCII characters (or a maximum of 85 three-byte characters in UTF-8 encoding). Because the alias is the key field in the Celerra Network Server’s iSCSI database, each alias must be unique on a given Data Mover. Aliases are case-sensitive (targets t1 and T1 can coexist on the same Data Mover).<pg_tag> = portal group tag (integer in the range 0 – 65535).<np_list> = network portal list, which is a comma-separated list of network portals in the portal group. Each network portal is given in the format <ip>[:<port>] where <ip> is the IP address and <port> is the listening TCP port. If the port is omitted, port 3260 is used."Network portals and portal groups" on page 78 provides more information about the use of network portals with iSCSI.Example:To create a target with the alias t1 and a network portal of 172.24.102.242 in portal group 100, type:$ server_iscsi server_2 -target -alias t1 -create 100:np=172.24.102.242

Output

server_2 : done

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Create an iSCSI LUNLUNs provide access to storage space on the server. To a client system, a Celerra iSCSI LUN appears as a disk device.

PrerequisitesWhen creating a destination LUN for iSCSI replication, the LUN must be read-only and the same size as the source LUN.

PostrequisitesTo improve performance when using the iSCSI LUN for Windows applications such as Microsoft Exchange, run the Microsoft diskpar utility to set the sector offset to 64 for proper alignment of the disk.

Action

To create an iSCSI LUN, use this command syntax:$ server_iscsi <movername> -lun -number <lun_number> -create <target_alias_name> -size <size>[M|G|T] -fs <fs_name> [-vp {yes|no}] [-readonly {yes|no}]

where:<movername> = name of the Data Mover.<lun_number> = number of the iSCSI LUN (an integer in the range 0 – 127). The LUN number must be unique on this Data Mover.<target_alias_name> = alias of the iSCSI target on which to create the LUN.<size> = size of the LUN in megabytes (M), gigabytes (G), or terabytes (T).<fs_name> = name of the file system on which to create the LUN.The resulting LUN is slightly smaller than the size you specify. Some of the space is needed for the underlying file system to fully allocate the LUN.Examples:To create a regular LUN, number 1, of 10 GB on target t1 on ufs1 on server_2, type:$ server_iscsi server_2 -lun -number 1 -create t1 -size 10G-fs ufs1

To create a virtually provisioned LUN, number 24, of 30 GB on target t2 on ufs1 on server_3, type:$ server_iscsi server_3 -lun -number 24 -create t2 -size 30G-fs ufs1 -vp yes

Output

server_2 : done

Note

If you include the option -vp yes to create a virtually provisioned LUN, the output includes the additional message:

Warning 17716815834: server_3 : You have just created a virtually provisioned (sparse) LUN. To avoid data unavailability and potential data loss when a file system is 100 percent full, monitor file system utilization to ensure the file system contains sufficient free space for LUN growth. For more information, refer to Configuring iSCSI Targets on Celerra available on the user documentation CD.

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Create an iSCSI LUN maskA LUN mask on a target controls iSCSI initiator access to the iSCSI LUNs on that target. Each LUN mask specifies the formal name of an iSCSI initiator and the LUN numbers it can access on the target.

PrerequisitesiSCSI SnapSure Manager for Exchange 2000 Help provides information about how to determine the IQN for an iSCSI initiator.

Unless you are using Celerra iSCSI targets in a clustered environment, do not grant multiple initiators access to the same LUN. Conflicts can occur if more than one initiator tries writing to the LUN.

If your environment requires multiple initiators to access the same LUN, you must create a mask for each initiator through a separate command.

Action

To create an iSCSI LUN mask, use this command syntax:$ server_iscsi <movername> -mask -set <target_alias_name> -initiator <initiator_name> -grant <access_list>

where:<movername> = name of the Data Mover<target_alias_name> = alias of the iSCSI target<initiator_name> = formal iSCSI name of the initiator<access_list> = comma-separated list of LUNs the initiator can accessExample:To create a LUN mask that enables the specified initiator to access LUNs 1, 3 through 5, and 7 on target t1 on Data Mover server_2, type:$ server_iscsi server_2 -mask -set t1 -initiator iqn.1991-05.com.microsoft:x86-39.nascse.emc -grant 1,3-5,7

Output

server_2 : done

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(Optional) Configure iSNS on the Data MoverWhen an iSNS client is configured on a Data Mover, the Data Mover registers all of its iSCSI targets with an external iSNS server. iSCSI initiators can query the iSNS server to discover the available targets.

PrerequisitesEnsure that the iSCSI service is stopped. Use the task "Stop the iSCSI service" on page 27.

Action

To configure iSNS on the Data Mover, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -set-server <IP>[:<port>]

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<IP> = IP address of the iSNS server<port> = port of the iSNS server (default is 3205)If the iSNS server is on a Microsoft cluster, use the IP address and port number of the cluster.Example:To configure server_2 to use the iSNS server at IP address 172.24.102.66 with the default port, type:$ server_iscsi server_2 -ns isns -set -server 172.24.102.66

Output

server_2 : done

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(Optional) Configure the ESI port for iSNSThe iSNS server uses the Entity Status Inquiry (ESI) port to monitor the status of the iSCSI service on the Data Mover. If an ESI port is not configured, one is assigned when the iSCSI service is started.

Action

To configure the ESI port for iSNS, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -set-esiport <port>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<port> = ESI port of the iSNS server (default is 3205)Example:To configure server_2 to use the ESI port for iSNS, type:$ server_iscsi server_2 -ns isns -set -esiport 3206

Output

server_2 : done

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(Optional) Create a CHAP entryThe CHAP entry specifies the secret to be exchanged between the Data Mover and an iSCSI initiator during authentication.

Action

To create a CHAP entry, use this command syntax:$ server_security {<movername> | ALL} -add -policy chap[-name <client_name>]

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers).<client_name> = formal iSCSI name for the initiator. For reverse authentication, use the keyword reverseauthentication.Example:To create a CHAP entry for server_2, type:$ server_security server_2 -add -policy chap -name iqn.1991-05.com.microsoft:winserver1.nasdoc.emc.com

Output Note

server_2 : Enter Secret:**************done

When prompted, type the secret (password) to be exchanged between the iSCSI initiator and the iSCSI target. The secret must be a minimum of 12 characters and a maximum of 256 characters. Windows operating systems support CHAP secrets of 12 to 16 characters.For reverse authentication, the Data Mover uses the same secret with any initiator.

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Start the iSCSI serviceThe iSCSI service must be running on a Data Mover to provide support for iSCSI activity with targets on the Data Mover.

Action

To start the iSCSI service, use this command syntax:$ server_iscsi {<movername> | ALL} -service -start

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To start the iSCSI service on all Data Movers, type:$ server_iscsi ALL -service -start

Output

server_2 : doneserver_3 : done

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Managing the iSCSI serviceThe tasks for managing the iSCSI service are:

◆ "Stop the iSCSI service" on page 27

◆ "Check the status of iSNS" on page 28

◆ "Change the iSNS configuration" on page 29

◆ "Clear iSNS configuration information" on page 30

◆ "Configure iSCSI digests" on page 31

◆ "View digest settings for the iSCSI service" on page 32

◆ "Control iSCSI discovery responses" on page 33

◆ "Control asynchronous event messages" on page 33

◆ "Enable or disable APTPL support for persistent reservation" on page 34

"(Optional) Configure iSNS on the Data Mover" on page 23 provides instructions for configuring the iSNS service. "Start the iSCSI service" on page 26 provides instructions for starting the iSCSI service.

Stop the iSCSI serviceBefore reconfiguring the iSCSI or iSNS services, you must stop the iSCSI service on a Data Mover. Stopping the iSCSI service on a Data Mover disconnects all iSCSI initiators connected to targets on the Data Mover. The initiators cannot log in again until the iSCSI service is restarted.

PrerequisitesEnsure that all iSCSI initiators are logged out from the target. Stopping the iSCSI service while an initiator is connected can cause the systems that host the iSCSI initiator to stop responding.

Action

To stop the iSCSI service, use this command syntax:$ server_iscsi {<movername> | ALL} -service -stop

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To stop the iSCSI service on all Data Movers, type:$ server_iscsi ALL -service -stop

Output

server_2 : doneserver_3 : done

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Check the status of iSNSStatus information for iSNS includes the state of the service (stopped or started), the IP address of the iSNS server, and the ESI port.

Action

To check the status of iSNS, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -info

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To check the status of iSNS for server_2, type:$ server_iscsi server_2 -ns isns -info

Output

server_2 :iSNS Client Service Status-------------------------- service : started server : 172.24.102.20:3205[tcp] state : SYNC entity : isns:00000001 source : iqn.1992-05.com.emc:apm000622024140000-4 ESI support : TRUE ESI port : 52635 ESI Time : UNKNOWN timeout : 3000 trace : FALSE PG support : TRUE

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Change the iSNS configurationIf you configured an iSNS client on the Data Mover as instructed in "(Optional) Configure iSNS on the Data Mover" on page 23, you might need to change the configuration to specify a new IP address for the iSNS server or a new ESI port for the Data Mover. You can also clear all iSNS configuration information.

PrerequisitesEnsure that the iSCSI service is stopped. To stop the service, use the task "Stop the iSCSI service" on page 27.

PostrequisitesAfter making any iSNS configuration change, restart the iSCSI service as described in "Start the iSCSI service" on page 26.

Action

To change the iSNS server, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -set-server <IP>[:<port>]

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<IP> = IP address of the iSNS server<port> = port of the iSNS server (default is 3205)If the iSNS server is on a Microsoft cluster, use the IP address and port number of the cluster.To change the ESI port for iSNS, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -set-esiport <port>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<port> = ESI port of the iSNS server (default is 3205)

Output Note

server_2 : done Changes to iSNS configuration settings do not take effect until the iSCSI service is restarted.

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Clear iSNS configuration informationIf you need to remove existing iSNS configuration information, perform this task.

PrerequisitesEnsure that the iSCSI service is stopped. To stop the service, use the task "Stop the iSCSI service" on page 27.

Action

To clear iSNS configuration information, use this command syntax:$ server_iscsi {<movername> | ALL} -ns isns -clear {-server | -esiport | -all}

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To clear the configured ESI port for server_2, type:$ server_iscsi server_2 -ns isns -clear -esiport

Output Note

server_2 : done Changes to iSNS configuration settings do not take effect until the iSCSI service is restarted.

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Configure iSCSI digestsHeader digests provide CRC error checking for PDU header segments. Data digests provide CRC error checking for data segments.

Action

To configure iSCSI digests, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi-modify <param_name> -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<param_name> = PreferHeaderDigest (for header digests) or PreferDataDigest (for data digests)<new_value> = 0 to disable or 1 to enable the parameterFacility and parameter names are case-sensitive.Examples:To disable header digests on server_2, type:$ server_param server_2 -facility iscsi -modify PreferHeaderDigest-value 0

To enable data digests on server_2, type:$ server_param server_2 -facility iscsi -modify PreferDataDigest-value 1

Output

server_2 : done

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View digest settings for the iSCSI serviceThe returned information indicates whether iSCSI data digests and header digests are enabled (preferred) or disabled (not preferred) on the Data Mover.

Action

To view digest settings for the iSCSI service, use this command syntax:$ server_iscsi {<movername> | ALL} -service -status

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To view digest settings for the iSCSI service on server_2, type:$ server_iscsi server_2 -service -status

Output

server_2 : **** ISCSI Service **** Status: Running Iscsi is configured to listen on ports: TCP Port: 3260 Header Digests are preferred Data Digests are not preferred [Session Stats]Session Failures: 0Last Session Failed: N/Z[Login/Logout Stats]Login Accepted: 0Login Failed: 0 Redirect: 0 Authorize: 0 Authenticate: 0 Negotiate: 0 Other: 0Logout Normal: 0Logout Other: 0Last Login Failed: N/A

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Control iSCSI discovery responsesYou can control whether iSCSI discovery returns information about targets that do not grant the initiator access to any LUNs. By default, discovery lists all targets even if a given target does not have a LUN mask for the initiator.

Control asynchronous event messagesUse this procedure to specify the type of asynchronous message sent to connected initiators when a LUN is added or removed. By default, Celerra targets send an asynchronous event message when the LUN inventory changes, but some initiators do not support this type of message.

Action

To control iSCSI discovery responses, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi -modify SendTargetsMode -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<new_value> = 0 to return information for all discovered targets, or 1 to return information only for targets that allow the initiator access to at least one LUNFacility and parameter names are case-sensitive.Example:To filter inaccessible targets on server_2 during discovery, type:$ server_param server_2 -facility iscsi -modify SendTargetsMode -value 1

Output

server_2 : done

Action

To control asynchronous event messages, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi -modify AsyncEvent -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<new_value> = 0 for asynchronous logout message, or 1 for asynchronous event messageFacility and parameter names are case-sensitive.Example:To send asynchronous logout messages on server_2, type:$ server_param server_2 -facility iscsi -modify AsyncEvent -value 0

Output

server_2 : done

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Enable or disable APTPL support for persistent reservationWhen Activate Persist Through Power Loss (APTPL) support is enabled, the server supports requests from a cluster to maintain persistent reservation information on nonvolatile storage. By default, APTPL support is disabled, so a SCSI persistent reservation command will fail if its APTPL bit is set. This setting applies to all iSCSI targets on the Data Mover.

PostrequisitesReboot the Data Mover to have the change take effect.

If you disable APTPL support, any PR information stored on disk is no longer available.

Action

To enable or disable APTPL support for persistent reservation, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi -modify EnableAptpl -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<new_value> = 0 to disable or 1 to enable APTPL supportFacility and parameter names are case-sensitive.Example:To enable APTPL support for iSCSI targets on server_2, type:$ server_param server_2 -facility iscsi -modify EnableAptpl -value 1

Output

server_2 : done

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Managing iSCSI targetsThe tasks for managing iSCSI targets are:

◆ "List iSCSI targets" on page 35

◆ "View iSCSI target properties" on page 36

◆ "View login statistics for an iSCSI target" on page 37

◆ "Rename an iSCSI target alias" on page 38

◆ "Change network portals for an iSCSI target" on page 39

◆ "Delete an iSCSI target" on page 40

"Create an iSCSI target" on page 20 provides instructions for creating iSCSI targets.

List iSCSI targetsYou can list all iSCSI targets configured on the server or on a specific Data Mover.

Action

To list iSCSI targets, use this command syntax:$ server_iscsi {<movername> | ALL} -target -list

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To list all iSCSI targets, type:$ server_iscsi ALL -target -list

Output

server_2 :alias_name portal_groups iscsi_namet1 iqn.1992-05.com.emc:apm000517032530000-1t2 100 iqn.1992-05.com.emc:apm000517032530000-5

server_3 :alias_name portal_groups iscsi_namet1 iqn.1992-05.com.emc:apm000517032530000-2

server_4 : no iscsi target entryserver_5 :alias_name portal_groups iscsi_namet1 iqn.1992-05.com.emc:apm000517032530000-4

Note

The output displays these fields:alias_name = alias for the target’s formal iSCSI nameportal_groups = portal groups used by the target (if any)iscsi_name = target’s formal iSCSI name

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View iSCSI target propertiesYou can view the properties for an iSCSI target, including the target’s formal iSCSI name, LUN information, and connected iSCSI initiators.

Action

To view iSCSI target properties, use this command syntax:$ server_iscsi {<movername> | ALL} -target -info {<alias_name> | -all}

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<alias_name> = alias of the iSCSI targetExample:To view iSCSI target properties for server_2, type:$ server_iscsi server_2 -target -info t1

Output

server_2 :Target Alias Name: t1Target iSCSI Name: iqn.1992-05.com.emc:apm000517032530000-1Serial Number: 1Logical Units: 2 : (Production) fsid=23 size=30MB alloc=0MB virtually_provisioned path=/ufs1/fs23_T1_LUN2_APM00051703253_0000/fs23_T1_LUN2_APM00051703253_0000 24 : (Production) fsid=23 size=10MB alloc=0MB dense path=/ufs1/fs23_T1_LUN24_APM00051703253_0000/fs23_T1_LUN24_APM00051703253_0000 25 : (Production) fsid=25 size=195MB alloc=0MB dense path=/ufs2/fs25_T1_LUN25_APM00051703253_0000/fs25_T1_LUN25_APM00051703253_0000 26 : (Production) fsid=23 size=8MB alloc=0MB dense path=/ufs1/fs23_T1_LUN26_APM00051703253_0000/fs23_T1_LUN26_APM00051703253_0000Connected Initiators: iqn.1991-05.com.microsoft:winserver3

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View login statistics for an iSCSI targetLogin statistics include the number of current iSCSI sessions and information about successful and failed login attempts.

Action

To view login statistics for an iSCSI target, use this command syntax:$ server_iscsi {<movername> | ALL} -target -stat {<alias_name> | -all}

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<alias_name> = alias of the iSCSI targetExample:To view login statistics for an iSCSI target for server_2, type:$ server_iscsi server_2 -target -stat t1

Output

server_2 : Target Alias Name: t1 Target iSCSI Name: iqn.1992-05.com.emc:apm000436006550000-1 [Login/Logout Stats] Login Accepted: 0 Login Failed: 0 Redirect: 0 Authorize: 0 Authenticate: 0 Negotiate: 0 Other: 0 Logout Normal: 0 Logout Other: 0 Last Login Failed: N/A [Session Stats]

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Rename an iSCSI target aliasYou can modify the alias for an iSCSI target, which is an alternative to the target’s formal iSCSI name. The formal iSCSI name for a target is permanent and cannot be changed.

Action

To rename an iSCSI target alias, use this command syntax:$ server_iscsi <movername> -target -rename <old_alias_name> <new_alias_name>

where:<movername> = name of the Data Mover.<old_alias_name> = current alias of the target.<new_alias_name> = new alias for the target. The alias is an alphanumeric string of as many as 255 ASCII characters (or a maximum of 85 3-byte characters in UTF-8 encoding). Because the alias is the key field in the Celerra Network Server’s iSCSI database, each alias must be unique on a given Data Mover. Aliases are case-sensitive (so targets t1 and T1 can coexist on the same Data Mover).Example:To change the target alias t1 on server_2 to tgt1, type:$ server_iscsi server_2 -target -rename t1 tgt1

Output

server_2 : done

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Change network portals for an iSCSI targetActive sessions between the target and any iSCSI initiators are not affected by network portal modifications. The new settings take effect after initiator logs out and ends the session, and apply the next time the initiator tries to log in.

Action

To change a network portal for an iSCSI target, use this command syntax:$ server_iscsi <movername> -target -bind <alias_name> <pg_tag>:np=<np_list>

To remove network portal information from a target, use this command syntax:$ server_iscsi <movername> -target -unbind <alias_name> {<pg_tag> | np=<np_list>}

where:<movername> = Data Mover on which to create the target.<alias_name> = alias of the iSCSI target.<pg_tag> = portal group tag (integer in the range 0 – 65535).<np_list> = network portal list, which is a comma-separated list of network portals in the portal group. Each network portal is given in the format <ip>[:<port>] where <ip> is the IP address and <port> is the listening TCP port. If the port is omitted, port 3260 is used."Network portals and portal groups" on page 78 provides more information about the use of network portals with iSCSI.Example:To add the network portal 172.24.102.243 in portal group 200 to target t1 on server_2, type:$ server_iscsi server_2 -target -bind t1 200:np=172.24.102.243

Output

server_2 : done

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Delete an iSCSI targetDeleting an iSCSI target deletes the target and all its associated LUN masks. Deleting a target also deregisters the target from the iSNS server.

PrerequisitesEnsure that all iSCSI initiators are logged out from the target.

Delete all LUNs on the target as described in "Delete an iSCSI LUN" on page 49.

Action

To delete an iSCSI target, use this command syntax:$ server_iscsi <movername> -target -delete <alias_name>

where:<movername> = name of the Data Mover<alias_name> = alias of the iSCSI targetExample:To delete an iSCSI target for server_2, type:$ server_iscsi server_2 -target -delete t5

Output

server_2 : done

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Managing iSCSI LUNsThe tasks for managing iSCSI LUNs are:

◆ "List iSCSI LUNs" on page 41

◆ "View iSCSI LUN properties" on page 42

◆ "Change an iSCSI LUN to read-only" on page 43

◆ "Change an iSCSI LUN to read/write" on page 44

◆ "View read/write statistics for an iSCSI LUN" on page 45

◆ "Extend an iSCSI LUN" on page 46

◆ "Update a Windows host after extending an iSCSI LUN" on page 47

◆ "Update a Linux host after extending an iSCSI LUN" on page 48

◆ "Delete an iSCSI LUN" on page 49

◆ "Configure the maximum number of LUNs per target" on page 50

"Create an iSCSI LUN" on page 21 provides instructions for creating iSCSI LUNs.

List iSCSI LUNs

Action

To list all iSCSI LUNs on a Data Mover or list the iSCSI LUNs for a specific target, use this command syntax:$ server_iscsi {<movername> | ALL} -lun -list

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)Example:To list iSCSI LUNs for server_2, type:$ server_iscsi server_2 -lun -list

Output

server_2 :target: t1lun size(MB) filesystem2 30 ufs1 ( id=23 )24 10 ufs1 ( id=23 )25 195 ufs2 ( id=25 )26 8 ufs1 ( id=23 )

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View iSCSI LUN properties

Action

To view the properties for an iSCSI LUN, which include the LUN number, target, LUN size, and role in an iSCSI replication relationship, use this command syntax:$ server_iscsi {<movername> | ALL} -lun -info {<lun_number> | -all}

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<lun_number> = number of the iSCSI LUNExample:To view iSCSI LUN properties for server_2, type:$ server_iscsi server_2 -lun -info 24

Output

server_2 :Logical Unit 24 on target t1: (Production) fsid=23 size=10MB alloc=0MB dense path=/ufs1/fs23_T1_LUN24_APM00051703253_0000fs23_T1_LUN24_APM00051703253_0000 replication=none max_extension_size=0MB

Note

A LUN is read/write unless its replication type is destination or available destination (which indicates a read-only LUN).If you create a snapshot of a production LUN (either regular or virtually provisioned), and then promote that snapshot, the command output can show an allocated space of 0 MB (alloc=0MB) for the production LUN (PLU) and for the promoted snapshot (temporary writable snapshot or TWS). The PLU and the TWS share the used blocks with the snapshot file, which is the owner of the allocated blocks.

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Change an iSCSI LUN to read-onlyChanging a LUN to read-only while it is being accessed by a host can interrupt data transfer operations that are pending or in progress, possibly causing data corruption. If the LUN’s mask grants access to an iSCSI initiator and that initiator is logged in to the target that contains the LUN, the -readonly yes option fails unless the -Force option is included.

Before using the -Force option, flush any cached or unwritten data to the LUN by unmounting and then remounting the file system that contains the LUN.

Action

To change an iSCSI LUN from read/write to read-only, use this command syntax:$ server_iscsi <movername> -lun -modify <lun_number> -target <target_alias_name> -readonly yes [-Force]

where:<movername> = name of the Data Mover<lun_number> = number of the iSCSI LUN<target_alias_name> = alias of the iSCSI targetExample:To change LUN 11 (a read/write LUN) on target t1 on server_2 to a read-only LUN, type:$ server_iscsi server_2 -lun -modify 11 -target t1 -readonly yes

Output

server_2 : done

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Change an iSCSI LUN to read/writePrerequisitesTo create a replication-based iSCSI clone LUN, use a replication application to copy the production LUN to a destination LUN. Delete all replication sessions associated with the destination LUN (either as a source or a destination), and then use this procedure to change the LUN to read/write.

PostrequisitesTo use a replication-based clone LUN with Windows Server 2003, you must also remove the VSS read-only and hidden bits from the LUN by using the diskpart utility or the script RmMountVolume.bat provided with Replication Manager.

Action

To change an iSCSI LUN from read-only to read/write, use this command syntax:$ server_iscsi <movername> -lun -modify <lun_number> -target <target_alias_name> -readonly no

where:<movername> = name of the Data Mover<lun_number> = number of the iSCSI LUN<target_alias_name> = alias of the iSCSI targetExample:To change LUN 24 (a read-only LUN) on target t1 on server_2 to a read/write LUN, type:$ server_iscsi server_2 -lun -modify 24 -target t1 -readonly no

Output

server_2 : done

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View read/write statistics for an iSCSI LUN

Action

To display read/write statistics for an iSCSI LUN, use this command syntax:$ server_iscsi <movername> -lun -stat {<lun_number> | -all} [-target <target_alias_name>]

where:<movername> = name of the Data Mover<lun_number> = number of the iSCSI LUN<target_alias_name> = name of the iSCSI target on which the LUN residesExample:To display read/write statistics for an iSCSI LUN for server_2, type:$ server_iscsi server_2 -lun -stat 24

Output

server_2 : Logical Unit 24 on target t1: (Production) fsid=23 size=20MB alloc=0MB dense path=/ufs1/fs23_T1_LUN24_APM00043600655_0000/fs23_T1_LUN24_APM00043600655_0000 replication=available destination max_extension_size=372MBStatistics: Total SCSI CDBs: 1139 Read: 519 Failed: 0 Blks read: 26609 Write: 451 Failed: 0 Blks written: 37299

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Extend an iSCSI LUN

PostrequisitesYou must run the appropriate utilities on the iSCSI host system to expand the host volume on the extended LUN:

◆ "Update a Windows host after extending an iSCSI LUN" on page 47

◆ "Update a Linux host after extending an iSCSI LUN" on page 48

You cannot restore the extended LUN by using any snapshot taken before the LUN was extended. If your organization uses LUN snapshots, consider taking a new snapshot of a LUN immediately after extending it. "Managing snapshots of iSCSI LUNs" on page 58 provides additional information.

Action

To extend the size of an iSCSI LUN after its initial creation, use this command syntax:$ server_iscsi <movername> -lun -extend <lun_number> -target <target_alias_name> -size <size>[M|G|T]

where:<movername> = name of the Data Mover<lun_number> = number of the iSCSI LUN<target_alias_name> = alias of the iSCSI target<size> = size to add in megabytes (M, the default), gigabytes (G), or terabytes (T)Example:To extend LUN 24 on target t1 on server_2 by 4096 MB, type:$ server_iscsi server_2 -lun -extend 24 -target t1 -size 4096M

Output

server_2 : done

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Update a Windows host after extending an iSCSI LUNIf an NTFS volume is configured on the extended LUN, you need to run the Windows diskpart utility to expand the volume to use the additional space.

PrerequisitesEnsure that the host system has the diskpart utility, which is included on Windows Server 2003. Otherwise, the utility can be downloaded from the Microsoft website.

If the disk has more than one volume, only the last can be extended.

Step Action

1. Open a Windows command prompt and type:diskpart.exe

Microsoft recommends using Safe mode or Active Directory Restore mode when extending an NTFS partition. Otherwise the process might fail, possibly resulting in file system corruption.

2. For Windows 2000 Server:a. Log out the initiator from the target.b. Log in again.For Windows Server 2003, type:

rescan

The diskpart utility rescans the disk and discovers the additional space on the LUN.

3. Type:list volume

The diskpart utility displays information about the available volumes.

4. Type:select volume <volume_number>

where:<volume_number> = number of the unformatted volume

5. Type:extend

The diskpart utility extends the last (or only) volume to include the newly available space.

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Update a Linux host after extending an iSCSI LUNAfter extending an iSCSI LUN, use this procedure to enable the Linux host to recognize the new LUN size.

Step Action

1. Unmount the extended LUN:# unmount <filesystem_directory>

2. Rescan (stop and restart) the SCSI bus on the host to view the extension:# /etc/init.d/iscsi stop# /etc/init.d/iscsi start

3. Using fdisk, resize the LUN on the host:# fdisk /dev/sd<drive>Command (m for help): d (delete a partition)Command (m for help): n (add a new partition)Command actione extendedp primary partition (1-4)

pPartition number (1-4): <partition_number>First cylinder (1-6120, default 1): 1Last cylinder or +size or +sizeM or +sizeK (1-6120, default 6120):6120Command (m for help): w (write table to disk and exit)

4. Resize the file system on the host:# e2fsck -f /dev/sd<drive><partition_number># resize2fs /dev/sd<drive><partition_number>

5. Remount the LUN on the host:# mount /dev/sd<drive><partition_number> <filesystem_directory>

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Delete an iSCSI LUNYou might want to delete a LUN when the data stored on that LUN is no longer needed. When you delete a LUN, all the data in the LUN is deleted as well.

PrerequisitesEnsure that no iSCSI initiator is connected to the LUN. Also, ensure that the LUN has no iSCSI snapshots. If necessary, use the procedure "Delete a snapshot" on page 62.

Action

To delete an iSCSI LUN, use this command syntax:$ server_iscsi <movername> -lun -delete <lun_number> -target <target_alias_name>

where:<movername> = name of the Data Mover<lun_number> = number of the iSCSI LUN<target_alias_name> = alias of the iSCSI targetExample:To delete LUN 25 on target t1 on server_2, type:$ server_iscsi server_2 -lun -delete 25 -target t1

Output

server_2 : done

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Configure the maximum number of LUNs per targetTo comply with the Windows limitation on the number of iSCSI LUNs per target, Windows-compatible mode, which is enabled by default on the Data Mover, allows a maximum of 255 LUNs (numbered 0 through 254) per target. If you use a non-Windows iSCSI initiator, you can disable Windows-compatible mode to allow a maximum of 256 LUNs (numbered 0 through 255) per target.

Action

To configure the maximum number of LUNs per target, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi -modify WinCompat -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<new_value> = 0 to allow 256 LUNs per target or 1 to enforce the Windows limit of 255 LUNs per targetFacility and parameter names are case-sensitive.Example:To disable Windows-compatible mode on server_2, type:$ server_param server_2 -facility iscsi -modify WinCompat -value 0

Output

server_2 : done

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Managing iSCSI LUN masksThe tasks for managing iSCSI LUN masks are:

◆ "List iSCSI LUN masks for a target" on page 51

◆ "Change grants for an iSCSI LUN mask" on page 52

◆ "Delete an iSCSI LUN mask" on page 53

"Create an iSCSI LUN mask" on page 22 provides instructions for creating iSCSI LUN masks.

List iSCSI LUN masks for a targetEach mask entry shows the initiator name and the LUNs to which the initiator is granted access.

Action

To list iSCSI LUN masks for a target, use this command syntax:$ server_iscsi <movername> -mask -list [<target_alias_name>]

where:<movername> = name of the Data Mover<target_alias_name> = alias of the iSCSI target. If omitted, masks for all targets on the Data Mover are listedExample:To list LUN masks on target t1 on server_2, type:$ server_iscsi server_2 -mask -list t1

Output

server_2 :target: t1initiator_name grant LUNsiqn.2005-12.com.emc:tech.pub.celerra 24-26,30iqn.1991-05.com.microsoft:winserver1.nasdoc.emc.com 1,3-5,7

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Change grants for an iSCSI LUN maskChanges to LUN masks take effect immediately. If you remove access to a LUN while the initiator has an active session with that LUN, the session is terminated, and the applications that are using the associated LUNs are interrupted.

PrerequisitesUse LUN numbers 0 through 127 for production LUNs (PLUs) and grant initiators access to LUNs in this range only.

Unless you are using Celerra iSCSI targets in a clustered environment, do not grant two initiators access to the same LUN. Granting multiple initiators access to the same LUN can cause conflicts when more than one initiator tries writing to the LUN. If the LUN is formatted with the NTFS file system in Windows, simultaneous writes might corrupt the NTFS file system on the LUN. Avoid granting an initiator access to an undefined LUN.

Action

To change grants for an iSCSI LUN mask, use this command syntax:$ server_iscsi <movername> -mask -set <target_alias_name> -initiator <initiator_name> {-grant <access_list> | -deny <access_list>}

where:<movername> = name of the Data Mover<target_alias_name> = alias of the iSCSI target<initiator_name> = formal iSCSI name of the initiator<access_list> = comma-separated list of LUNsDo not remove access to a promoted snapshot. Promoted snapshots typically use LUN numbers 128 and greater. If you change a LUN mask for a target with a promoted snapshot, the snapshot is no longer accessible.Example:To add access to LUN 30 on target t1 on server_2 for the specified initiator, type:$ server_iscsi server_2 -mask -set t1 -initiator iqn.1991-05.com.microsoft:t105.nascse.emc -grant 30

To remove access to LUN 24 on target t1 on server_2 for the specified initiator, type:$ server_iscsi server_2 -mask -set t1-initiator iqn.1991-05.com.microsoft:t105.nascse.emc -deny 24

Output

server_2 : done

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Delete an iSCSI LUN maskAfter a LUN mask is deleted, the associated initiator has no access to LUNs on the target. If you delete the LUN mask for an initiator with an active session, the session is terminated immediately, and the applications that are using the associated LUNs are interrupted.

Action

To delete an iSCSI LUN mask, use this command syntax:$ server_iscsi <movername> -mask -clear <target_alias_name> -initiator <initiator_name>

where:<movername> = name of the Data Mover<target_alias_name> = alias of the iSCSI target<initiator_name> = formal iSCSI name of the initiatorExample:To delete a LUN mask on target t1 on server_2 , type:$ server_iscsi server_2 -mask -clear t1 -initiator iqn.1991-05.com.microsoft:t105.nascse.emc

Output

server_2 : done

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Managing CHAP authenticationThe tasks for managing CHAP authentication are:

◆ "Enforce CHAP authentication" on page 54

◆ "View CHAP entries" on page 55

◆ "Change a CHAP secret" on page 56

◆ "Delete a CHAP entry" on page 57

"(Optional) Create a CHAP entry" on page 25 provides instructions for creating CHAP entries.

Enforce CHAP authenticationEnforcement of CHAP authentication is disabled by default. You can enable it by modifying the server parameters RequireChap and RequireDiscoveryChap.

Action

To enforce CHAP authentication, use this command syntax:$ server_param {<movername> | ALL} -facility iscsi -modify <param_name> -value <new_value>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers)<param_name> = name of the parameter<new_value> = 0 to disable or 1 to enable the parameterFacility and parameter names are case-sensitive.Examples:To enforce CHAP authentication for regular login sessions on server_2, type:$ server_param server_2 -facility iscsi -modify RequireChap -value 1

To enforce CHAP authentication for discovery login sessions on server_2, type:$ server_param server_2 -facility iscsi -modify RequireDiscoveryChap -value 1

Output

server_2 : done

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View CHAP entriesEach CHAP entry indicates either the formal iSCSI name of the initiator or a label that indicates reverse authentication is used.

Action

To view CHAP entries, use this command syntax:$ server_security {<movername> | ALL} -info -policy chap [-name <client_name>]

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers).<client_name> = formal iSCSI name for the initiator. For reverse authentication, use the keyword reverseauthentication.Example:To list CHAP entries for all Data Movers, type:$ server_security ALL -info -policy chap

Output Note

server_2 : chapdb name=iqn.2005-11.com.emc:nasinitiator pass=********

server_3 : chapdb name=reverseAuthentication pass=********

For security, the current CHAP secret is not shown.

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Change a CHAP secretIf there is an active session between the initiator and target, changes to the CHAP secret do not take effect until the initiator logs out from the target and the session ends.

Action

To change a CHAP secret, use this command syntax:$ server_security {<movername> | ALL} -modify -policy chap -name <client_name>

where:<movername> = name of the Data Mover (or keyword ALL for all Data Movers).<client_name> = formal iSCSI name for the initiator. For reverse authentication, use the keyword reverseauthentication.Example:To change the CHAP secret on server_2 for the specified initiator, type:$ server_security server_2 -modify -policy chap -name iqn.1991-05.com.microsoft:winserver1.nasdoc.emc.com

Output Note

server_2 : Enter Secret:**************done

When prompted, type the new secret. The secret must be a minimum of 12 characters and a maximum of 256 characters. Windows operating systems support CHAP secrets of 12 to 16 characters.For reverse authentication, the Data Mover uses the same secret with every initiator.

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Delete a CHAP entryDeletion of a CHAP entry does not affect existing sessions. If you delete the Reverse Authentication entry for the Data Mover and an initiator requires target authentication, the initiator cannot establish a session with the target.

Action

To delete a CHAP entry, use this command syntax:$ server_security {<movername> | ALL} -delete -policy chap [-name <client_name>]

where:<movername> = name of the Data Mover.<client_name> = formal iSCSI name for the initiator. For reverse authentication, use the keyword reverseauthentication.Example:To delete the CHAP secret on server_2 for the specified initiator, type:$ server_security server_2 -delete -policy chap -name iqn.1991-05.com.microsoft:winserver1.nasdoc.emc.com

Output

server_2 : done

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Managing snapshots of iSCSI LUNsThe tasks for managing snapshots are:

◆ "List snapshots" on page 58

◆ "View information about a snapshot" on page 59

◆ "Create a snapshot" on page 60

◆ "Modify the application data associated with a snapshot" on page 61

◆ "Delete a snapshot" on page 62

◆ "Restore a production LUN from a snapshot" on page 63

◆ "Promote a snapshot" on page 64

◆ "Demote a snapshot" on page 65

Each of these operations requires established CHAP authentication between the Control Station where the command is issued and the Data Mover where the iSCSI target, LUN, or snapshot resides.

For information about replicating snapshots of iSCSI LUNs, refer to these documents:

◆ Using EMC Celerra Replicator for iSCSI (V1)

◆ Using EMC Celerra Replicator (V2)

List snapshots

Action

To lists all iSCSI LUN snapshots on the specified Data Mover or all snapshots of a specified iSCSI LUN, regardless of the application used to create the snapshots, use this command syntax:$ server_iscsi <movername> -snap -list [-target <target_alias_name> -lun <lun_number>]

where:<movername> = name of the Data Mover<target_alias_name> = alias of the iSCSI target<lun_number> = number of the iSCSI LUNExample:To list the snapshots of LUN 24 on target t2, type:$ server_iscsi server_2 -snap -list -target t2 -lun 24

Output

server_2:Snap Name Lun Number Target Create Timefs103_T1_LUN24_FCNBD054507021_003C.ckpt006 24 t2 Thu Mar 06 14:33:09 EST 2008fs103_T1_LUN24_FCNBD054507021_003C.ckpt005 24 t2 Thu Mar 06 14:29:22 EST 2008

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View information about a snapshotThis operation displays information about a specific snapshot: its name, the LUN number and target, LUN size, application label, when the snapshot was created, and any associated application data (or “(non-printable characters)” if the data is not UTF-8 compliant). If the snapshot is promoted, the output includes the promoted LUN number and the IQN of initiator that can access the LUN.

Action

To view information about a snapshot, use this command syntax:$ server_iscsi <movername> -snap -info <snap_name>

where:<movername> = name of the Data Mover<snap_name> = name of the snapshotExample:To view information on server_2 for the specified snapshot, type:$ server_iscsi server_2 -snap -info fs14_T8_LUN24_000183500235_0006.ckpt008

Output

server_2:Snap Name = fs14_T8_LUN24_000183500235_0006.ckpt008Lun Number = 9Target = t1 Promoted Number = Promoted Initiator = Application Label = CelerraCS LUN Size MB = 3 Create Time = Wed Mar 05 11:30:52 EST 2008Application Data =

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Create a snapshotThis operation creates a snapshot of an iSCSI LUN. The snapshot is crash consistent (as if after a power loss), but not necessarily consistent from the viewpoint of host applications.

PrerequisitesEnsure that enough space is available to support the new snapshot. In addition, each LUN can support a maximum of 2000 snapshots.

Although the snapshot supports as many as 4096 bytes of application data, the CLI might limit the number of characters you can type in the server_iscsi command.

PostrequisitesTo get the name of the new snapshot, use the task "List snapshots" on page 58.

Action

To create a snapshot, use this command syntax:$ server_iscsi <movername> -snap -create -target <target_alias_name> -lun <lun_number> [-data <app_data>]

where:<movername> = name of the Data Mover.<target_alias_name> = alias of the iSCSI target.<lun_number> = number of the iSCSI LUN.<app_data> = comment text (maximum of 4096 bytes). If the text includes a space character, enclose the entire comment within double quotation marks.Example:To create a snapshot of LUN 24 on target t2 on server_2 and include the specified comment text, type:$ server_iscsi server_2 -snap -create -target t2 -lun 24 -data “Q3 analysis snap Target t2 LUN 24”

Output

server_2 : Info 26306936878: OK.id=fs23_t1_LUN24_HK190807300021_0000.ckpt000

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Modify the application data associated with a snapshotThis operation replaces any application data associated with a snapshot with the supplied text. If the snapshot has no application data, the text is added.

PrerequisitesThe snapshot must be one created through the server_iscsi command (that is, its application label must be CelerraCS). If the snapshot was created by a host-based application (such as CBMCLI or Replication Manager), use the same application to modify the application data.

Although a snapshot supports as many as 4096 bytes of application data, the CLI might limit the number of characters you can type in the server_iscsi command.

Action

To modify the application data associated with a snapshot, use this command syntax:$ server_iscsi <movername> -snap -modify <snap_name> -data <app_data>

where:<movername> = name of the Data Mover.<snap_name> = name of the snapshot.<app_data> = new comment text (maximum of 4096 bytes). If the text includes a space character, enclose the entire comment within double quotation marks. To clear existing data, provide a null string (““).Example:To associate the specified comment text with the specified snapshot on server_2, replacing any existing comment text or binary data, type:$ server_iscsi server_2 -snap -modify fs14_T8_LUN24_000183500235_0006.ckpt010 -data “Q3 analysis snap Target t2 LUN 24”

Output

server_2 : OK

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Delete a snapshotThis operation deletes either the specified snapshot or all snapshots of the specified iSCSI LUN.

PrerequisitesTo delete a snapshot created by a host-based application (such as CBMCLI or Replication Manager), include the -Force option.

You cannot delete a snapshot while it is promoted, or any more recent snapshot of the same LUN (even with the -Force option). If necessary, use the task "Demote a snapshot" on page 65.

Action

To delete a snapshot, use this command syntax:$ server_iscsi <movername> -snap -delete {<snap_name> | -target <target_alias_name> -lun <lun_number>} [-Force]

where:<movername> = name of the Data Mover<snap_name> = name of the snapshot <target_alias_name> = alias of the iSCSI target<lun_number> = number of the iSCSI LUNExample:To delete all snapshots of LUN 24 on target t2 on server_2, regardless of the application that created the snapshot, type:$ server_iscsi server_2 -snap -delete -target t2 -lun 24 -Force

Output

server_2 : OK

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Restore a production LUN from a snapshotThis operation restores the content of a production iSCSI LUN from a snapshot of that LUN on the same target. The snapshot used for the LUN restoration is preserved, but all newer snapshots of that LUN are deleted.

PrerequisitesEnsure that the production LUN is read-only. If necessary, use the task "Change an iSCSI LUN to read-only" on page 43.

The snapshot and the production LUN must be the same size. If the production LUN was extended after the snapshot was taken, you cannot restore from that snapshot.

You cannot restore from a snapshot if it, or a more recent snapshot of the LUN, is promoted. If necessary, use the task "Demote a snapshot" on page 65.

Action

To restore a production LUN from a snapshot, use this command syntax:$ server_iscsi <movername> -snap -restore <snap_name>

where:<movername> = name of the Data Mover<snap_name> = name of the snapshotExample:To restore a specific LUN from a specific snapshot, type:$ server_iscsi server_2 -snap -restore fs14_T8_LUN24_000183500235_0006.ckpt008

Output Note

server_2 : OK

If the server is rebooted while a restore operation is in progress, the command returns a generic error.After the server reboots, the restore operation should complete successfully.

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Promote a snapshotThis operation promotes a snapshot and mounts it as a temporary iSCSI LUN. The new LUN has the same data content as the snapshot.

PrerequisitesBecause the snapshot will be mounted as a LUN, ensure that the target does not already have the maximum number of LUNs. The maximum is either 255 or 256, depending on the setting of the WinCompat server parameter on the Data Mover.

You cannot promote a snapshot that is already promoted. That is, you cannot use a single snapshot to mount multiple LUNs concurrently.

PostrequisitesThe mounted LUN is assigned the next available LUN number greater than 127. If none is available, the LUN is assigned the next available number in the range 0 through 127. To display the assigned LUN number for the promoted snapshot, use the task "View information about a snapshot" on page 59.

Action

To promote a snapshot, use this command syntax:$ server_iscsi <movername> -snap -promote <snap_name> -initiator <initiator_name>

where:<movername> = name of the Data Mover<snap_name> = name of the snapshot<initiator_name> = IQN of the iSCSI initiator allowed access to the promoted LUNExample:To promote the specified snapshot on server_2 and grant access to the specified iSCSI initiator, type:$ server_iscsi server_2 -snap -promote fs14_T8_LUN24_000183500235_0006.ckpt009 -initiator iqn.1991-05.com.microsoft:winserver1.nasdoc.emc.com

Output

server_2 : OK

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Demote a snapshotThis operation demotes a promoted snapshot and unmounts the associated LUN. All data written to the LUN is discarded and irretrievable.

PrerequisitesDemoting a snapshot while the LUN is in use can interfere with the host application and might cause the corruption or loss of data. If the LUN is in use by an iSCSI initiator, the operation fails unless the command includes the -Force option.

Action

To demote a snapshot, use this command syntax:$ server_iscsi <movername> -snap -Demote <snap_name> [-Force]

where:<movername> = name of the Data Mover<snap_name> = name of the promoted snapshotExample:To demote a specific snapshot on server_2, type:$ server_iscsi server_2 -snap -Demote fs14_T8_LUN24_000183500235_0006.ckpt010

Output

server_2 : OK

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TroubleshootingAs part of an effort to continuously improve and enhance the performance and capabilities of its product lines, EMC periodically releases new versions of its hardware and software. Therefore, some functions described in this document may not be supported by all versions of the software or hardware currently in use. For the most up-to-date information on product features, refer to your product release notes.If a product does not function properly or does not function as described in this document, please contact your EMC representative.

Where to get helpTo obtain EMC support, product, and licensing information:Product information – For documentation, release notes, software updates, or for information about EMC products, licensing, and service, go to the EMC Powerlink website (registration required) at http://Powerlink.EMC.com.Troubleshooting – For troubleshooting information, go to Powerlink, search for Celerra Tools, and select Celerra Troubleshooting from the navigation panel on the left.

Technical support – For technical support, go to EMC Customer Service on Powerlink. After logging in to the EMC Powerlink website, go to Support > Request Support. To open a service request through Powerlink, you must have a valid support agreement. Please contact your EMC Customer Support Representative for details about obtaining a valid support agreement or to answer any questions about your account.

Note: Please do not request a specific support representative unless one has already been assigned to your particular system problem.

Problem Resolution Roadmap for EMC Celerra contains additional information about using Powerlink and resolving problems.

EMC E-Lab Interoperability NavigatorThe EMC E-Lab™ Interoperability Navigator is a searchable, web-based application that provides access to EMC interoperability support matrices. It is available on the EMC Powerlink website at http://Powerlink.EMC.com. After logging in to Powerlink, go to Support > Interoperability and Product Lifecycle Information > E-Lab Interoperability Navigator.

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Troubleshooting checklistTo troubleshoot communication problems between iSCSI initiators and targets:

Step Action

1. Check the network connectivity:• Use the ping command to check connectivity from the iSCSI host to the IP address of

the target.• Use the server_ping command to check connectivity from a Data Mover to the iSCSI

host.When checking connectivity, use IP addresses to avoid name resolution issues. If ping works in one direction, but not the other, a netmask is probably set incorrectly somewhere.

2. Check the status of iSCSI services:• Is the iSCSI service started on the Data Mover? "Start the iSCSI service" on page 26

provides instructions for starting the iSCSI service.• Is the Microsoft iSCSI Initiator service started? Check the status from the Windows

Services window.• To see which initiators are currently logged in to the target, use this command syntax:server_iscsi <movername> -target -info <alias_name>

3. Check the portal settings for the target and initiator. Are they configured correctly?

4. Check the target’s LUN mask:• Is a LUN mask configured for the initiator?• Is the name of the initiator correct?• Does the mask grant access to appropriate LUNs?

5. Check the iSCSI names of the initiator and target. Do the names use a legal format? An IQN must be an identifier of up to 223 ASCII characters consisting of lowercase alphanumeric characters, and the dot, dash, and colon characters. The name must be globally unique.

6. If using CHAP authentication:• Is the initiator configured with the same CHAP secret as the target?• Does the CHAP entry on the target use the correct CHAP name?• If using two-way authentication, is Reverse Authentication configured on the Data

Mover with the same secret on the initiator?

7. Check the storage array to determine if it is functioning correctly.

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Error messagesAs of version 5.6, all new event, alert, and status messages provide detailed information and recommended actions to help you troubleshoot the situation. To view message details, use any of these methods:◆ Celerra Manager:

• Right-click an event, alert, or status message and select to view Event Details, Alert Details, or Status Details.

◆ Celerra CLI:

• Type nas_message -info <MessageID>, where MessageID is the message identification number.

◆ EMC Celerra Network Server Error Messages Guide:

• Use this guide to locate information about messages that are in the earlier-release message format.

◆ Powerlink:

• Use the text from the error message’s brief description or the message’s ID to search the Knowledgebase on Powerlink. After logging in to Powerlink, go to Support > Knowledgebase Search > Support Solutions Search.

Consult the server log for error messages related to iSCSI targets. These logging facilities report iSCSI-related error messages.

Logging facility Errors related to

ISCSI iSCSI service

VLU (virtual logical unit) iSCSI LUNs

IPSNS (IP storage naming service) iSNS

NBS (network block service) iSCSI snapshots

UFS (UNIX file system) iSCSI LUNs

VCS (version control system) iSCSI snapshots

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Table 3 on page 69 lists situations, their error messages or symptoms, their probable cause, and corrective action.

Table 3 iSCSI-related error messages (page 1 of 5)

SituationError message/Symptom Probable cause Corrective action

Unable to create a target

Target alias name is in use.

The specified alias is already in use on the Data Mover.

Aliases must be unique on a given Data Mover. Retry the command with a unique alias.

Target iSCSI name is not valid.

The format of the IQN is invalid. An IQN is a globally unique identifier of up to 223 characters. IQNs can contain lowercase alphanumeric characters and the dot, dash, and colon characters—other characters are invalid.

• Verify that the IQN does not contain invalid characters.

• Verify that the IQN does not contain too many characters.

• Verify the reverse domain name is entered correctly. For example, .com.emc is the reverse of emc.com.

Invalid argument <number exceeds 65535>.

The specified portal number is invalid.

Verify the network portal number.

Unable to delete a target

Target has one or more logical units remaining.

You cannot delete a target while LUNs are associated with it.

Delete the remaining LUNs, and then delete the target.

Unable to create a LUN

LUN <xx> must be less than 256.

The LUN number you entered exceeded 255.

When Windows-compatible mode is enabled, the valid range for LUNs is 0 through 255.

Unable to delete a LUN

Lun <xx> used by following initiators: iqn.<xx>. Lun <xx> in use, can’t be removed.

At least one iSCSI initiator is logged in to the LUN.

A LUN must be unmounted from the client before it can be deleted. Log out the iSCSI initiator from the target, and then unmount the LUN.

Unable to create a LUN mask

Failed, target <xx> not found.

Either the target does not exist or it is on a different Data Mover.

Create the target on the Data Mover or specify the Data Mover on which the target exists.

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Cannot add a portal to iSCSI initiator (discovery problem)

On the iSCSI initiator:Authentication Failure

The target requires CHAP authentication or reverse CHAP authentication for discovery. You entered either no CHAP secret or an incorrect secret for the initiator.

• If CHAP authentication is required, set a secret on the initiator side by selecting Log On > Advanced > CHAP logon information.

• If two-way authentication is required, set a secret on the initiator side by selecting Initiator Settings > Initiator CHAP secret.

iSCSI SnapSure Manager for Exchange 2000 Help provides information about configuring CHAP on the initiator.

On the iSCSI initiator:Connection Failed

Either:• The iSCSI service is not started

on the Data Mover.• The wrong socket (port) was

entered.

Either:• Start the iSCSI service on the

Data Mover as described in "Start the iSCSI service" on page 26.

• Enter the correct port number on the initiator side.

Cannot add a portal to iSCSI initiator (discovery problem)

In the Celerra server log:Initiator did not offer CHAP Authentication (required for discovery sessions).

The CHAP secret was not entered on the initiator.

From the iSCSI initiator, try to log in and enter the CHAP secret through Log On > Advanced > CHAP logon information.

Able to discover targets without using the CHAP secret even though CHAP is configured.

Either:• Target does not require CHAP

authentication for discovery.• iSNS is configured and supplies

the targets.

Set the RequireChap parameter on the Data Mover as described in "Enforce CHAP authentication" on page 54.

Table 3 iSCSI-related error messages (page 2 of 5)

SituationError message/Symptom Probable cause Corrective action

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Login problem On the iSCSI initiator:Authentication Failure

The target requires CHAP authentication or reverse CHAP authentication. You entered either no CHAP secret or an incorrect secret for the initiator.

• If CHAP authentication is required, set a secret on the initiator side by selecting Log On > Advanced > CHAP logon information.

• If two-way authentication is required, you must set a secret on the initiator side by selecting Initiator Settings > Initiator CHAP secret.

iSCSI SnapSure Manager for Exchange 2000 Help provides information about configuring CHAP on the initiator.

In the Celerra server log:CHAP authentication failure for initiator: iqn.<xx>.

Either the wrong secret or no secret is configured on the Data Mover.

Set an appropriate secret as described in "(Optional) Create a CHAP entry" on page 25.

Able to add a target portal without using the CHAP secret although CHAP is configured.

The target does not require CHAP authentication for discovery.

Set the parameter RequireDiscoveryChap on the Data Mover as described in "Enforce CHAP authentication" on page 54.

iSNS Multiple failures when trying to contact iSNS server.

The target cannot contact the iSNS server because:• Network issues prevent contact

with the iSNS server.• The iSNS service is not running

on the server.

Ping the iSNS server. Ensure that the iSNS server is online and that the correct iSNS IP address and port are configured on the Data Mover. "(Optional) Configure iSNS on the Data Mover" on page 23 provides configuration instructions.

Unable to take a snapshot a LUN

In the Celerra server log:Failed to create temp writable snap for <lun ID>.

Attempted to take a snapshot of the LUN through one of the Celerra iSCSI host applications, but the file system does not have enough room to create or mount the snapshot.

Extend the file system containing the LUN.

Table 3 iSCSI-related error messages (page 3 of 5)

SituationError message/Symptom Probable cause Corrective action

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LUN extension failed to extend file version <xx> err <xx>

Failed to extend the file version because of a version error.Check the actual version set error code.

Check the detailed file system error messages and take the action recommended in the error message.

failed to get version <xx> from file version set <xx> err <xx>!

Failed to locate the version file because of a version error.Check the actual version set error code.

Check the detailed file system error messages and take the action recommended in the error message.

failed to get Max Extend size for file version <xx> err <xx>

Failed to get the maximum extension size for a file version because of a version error.Check the actual version set error code.

Check the detailed file system error messages and take the action recommended in the error message.

Recover vlu <xx> size <xx> MB

The message might appear in the server log when the Data Mover starts up. The LUN database is not synchronized with the underlying version file object before recovery.

None.

updateLunrecord failed with UPDATE_INVAL_FMT for tgtRecId:<xx> lun:<xx>

An attempt to update a LUN record failed because of an invalid format.Error in updating LUN record.

Reboot the Data Mover to recover the database file and correct the problem.

updateLunrecord failed with UPDATE_NOT_FOUND for tgtRecId:<xx> lun:<xx>

An attempt to update a nonexisting LUN record results in failure.Error in updating LUN records or LUN database corruption.

None.

updateLunrecord failed, out of memory for tgtRecId:<xx> lun:<xx>

An attempt to update a LUN record failed because of an out-of-memory condition.Possible memory leak.

Reboot the Data Mover to recover the database file and correct the problem.

updateLunrecord failed with UPDATE_FILE_ERR for tgtRecId:<xx> lun:<xx>

An attempt to update a LUN record failed because of a file error.Possible root file system error.

Reboot the Data Mover to recover the database file and correct the problem.

Table 3 iSCSI-related error messages (page 4 of 5)

SituationError message/Symptom Probable cause Corrective action

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Customer training programsEMC customer training programs are designed to help you learn how EMC storage products work together and integrate within your environment to maximize your entire infrastructure investment. EMC customer training programs feature online and hands-on training in state-of-the-art labs conveniently located throughout the world. EMC customer training programs are developed and delivered by EMC experts. For program information and registration, log in to Powerlink, our customer and partner website, and select the Training menu.

LUN extension lunTorec: failed, out of memory for tgtRecId:<xx> lun:<xx>

An attempt to construct a LUN record failed because of an out-of-memory condition.

Reboot the Data Mover to recover the database file and correct the problem.

failed to locate file version set <xx> err <xx>

Failed to locate the file version set because of a version set error.Check the actual version set error code.

Reboot the Data Mover to recover the database file and correct the problem.

promoted snapshot lun cannot be extended!

A promoted snapshot LUN cannot be extended.

Abort the operation.

Table 3 iSCSI-related error messages (page 5 of 5)

SituationError message/Symptom Probable cause Corrective action

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Appendix: Understanding iSCSIInternet SCSI (iSCSI) is a transport protocol that enables host systems and storage devices to interoperate over TCP/IP networks. The iSCSI architecture is based on the client/server model in which an iSCSI host system (client) encapsulates SCSI packets and sends them to a storage device (server).

Each iSCSI host system must run one or more iSCSI initiators. Each storage device must have one or more iSCSI targets. An iSCSI initiator is a software device (sometimes with supporting hardware) installed on a host system (such as a server or desktop computer). The iSCSI initiator communicates with an iSCSI target installed on a storage device, such as a Celerra Network Server.

The term initiator refers to an iSCSI initiator and the term target refers to an iSCSI target.

While traditional parallel SCSI devices use a parallel SCSI bus as the interconnect between initiators and targets, iSCSI uses TCP/IP networks as the interconnect medium. A traditional SCSI storage device must be directly attached to a host system. The distance between the two is limited because traditional SCSI parallel cables cannot exceed 25 meters. In contrast, iSCSI solutions can manage storage over long distances across a TCP/IP network.

For detailed information, refer to these topics:

◆ "iSCSI protocol" on page 75

◆ "iSCSI network topologies" on page 76

◆ "iSCSI components" on page 77

◆ "iSCSI naming" on page 81

◆ "iSCSI discovery" on page 83

◆ "iSCSI authentication" on page 85

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iSCSI protocolThe iSCSI protocol enables initiators on a host to communicate with targets on a storage device and to exchange SCSI commands and data. Figure 2 on page 75 shows that the iSCSI protocol operates between the SCSI layer and the TCP layer in the protocol stack.

Figure 2 Protocol stack for iSCSI host and target systems

As data moves down the protocol stack on the host, it is first incorporated in SCSI command descriptor blocks (CDBs). The initiator encapsulates the CDB in an iSCSI protocol data unit (PDU), which is then enclosed in TCP and IP packet for transport. Figure 3 on page 75 shows the iSCSI encapsulation layers.

Figure 3 iSCSI encapsulation layers

On reaching a target, the IP and TCP layers are stripped off. The target interprets the PDUs and forwards the SCSI instructions or data to the LUNs on the storage device.

iSCSI Host System

CNS-000481

Data Link Layer

IP Layer

TCP Layer

iSCSI Initiator

SCSI Layer

Application

Data Link Layer

IP Layer

TCP Layer

SCSI Protocol

iSCSI Protocol

TCP

IP

Dat

a F

low

Dat

a F

low

Storage Device System(Celerra Data Mover)

Ethernet

iSCSI Target

LUN

IPPacket

TCPPacket

iSCSI ProtocolData Unit (PDU)

SCSI CommandDescriptor Block (CDB)

CNS-000434

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iSCSI network topologiesThere are two types of iSCSI network topologies—native and bridging.

NativeA native topology consists of Ethernet only and uses standard Ethernet switches and routers. Native topologies use iSCSI throughout the network and do not include any Fibre Channel. Figure 4 on page 76 shows a native iSCSI network topology. Celerra iSCSI is a native iSCSI solution.

Figure 4 Native iSCSI network topology

BridgingA bridging topology combines Ethernet and Fibre Channel networks through an iSCSI bridge. The servers connect to the network through Ethernet, and the storage devices are attached through Fibre Channel. Bridging topologies use the iSCSI protocol on the Ethernet network. Figure 5 on page 76 illustrates a bridging iSCSI network topology.

The Celerra iSCSI feature does not support the bridging topology.

Figure 5 Bridging iSCSI network topology

PS0 PS1 PS2 PS3 PS4 SMB0 SMB1

SB

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Clients and ApplicationServers

EthernetSwitch

CNS-000439

Storage Network

Clients and ApplicationServers

EthernetSwitch

CNS-000440

iSCSIBridge

Fibre Channel Network

PS0 PS1 PS2 PS3 PS4 SMB0 SMB1

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iSCSI componentsThese topics provide more information about components in iSCSI architecture and provide information needed when configuring targets on a Celerra Network Server:

◆ "iSCSI initiators and targets" on page 77

◆ "Network portals and portal groups" on page 78

◆ "LUNs and LUN masks" on page 79

iSCSI initiators and targetsThe iSCSI protocol consists of two basic components—the iSCSI initiator and the iSCSI target—known collectively as iSCSI nodes. Each node is identified by a unique iSCSI name. "iSCSI naming" on page 81 provides details. Figure 6 on page 77 shows how the initiator resides on the client system and issues commands to the target, which resides on a storage device.

Figure 6 Initiator and target relationship

The initiator:

◆ Encapsulates SCSI commands, data, and status information in iSCSI PDUs.

◆ Logs in to the target and establishes an iSCSI session.

◆ Discovers the LUNs associated with the target, as described in "LUNs and LUN masks" on page 79.

◆ Sends the PDUs to the target.

The initiator is the active component in iSCSI communications and initiates communication with the target. In almost all cases, the target only responds to requests from the initiator and does not initiate independent action.

The initiator can be either a software device, such as the Microsoft iSCSI Initiator, or a hardware component, such as an iSCSI host bus adapter (HBA). To enable communication with the target, the initiator is bound to a network interface or portal, which is identified by an IP address, as described in "Network portals and portal groups" on page 78.

Targets

The target:

◆ Receives requests sent by the initiator through a TCP connection.

◆ Extracts the SCSI commands from the PDU.

◆ Routes SCSI tasks to corresponding LUNs for execution.

◆ Sends status, data, and sense data back to the initiator.

iSCSIInitiator

iSCSITarget

Host System Storage Device

IP Network

CNS-000429

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The target can be either a software device, such as a Celerra iSCSI target, or a hardware component on an iSCSI HBA.

Network portals and portal groupsBoth initiators and targets use network interfaces, called network portals, to communicate over the network. For an initiator, the network portal is identified solely by its IP address. For a target, the network portal is identified by its IP address and TCP listening port as shown in Figure 7 on page 78.

Figure 7 Initiator, target, and network portal relationship

Initiators and targets can use multiple portals. Because an initiator’s portals are identified by IP address, each network portal bound to an initiator requires a unique IP address. Because target portals are identified by IP address and TCP port, target portals can share an IP address as long as each portal uses a unique TCP port. In addition, multiple targets can use the same portal, as shown in Figure 8 on page 78.

Figure 8 Two iSCSI targets sharing a network portal

By default, iSCSI uses port 3260, but it can listen on any unused port. Although many organizations use the default port for iSCSI, you might want to select other ports for more security.

Portal groups

iSCSI also uses the concept of a portal group. A portal group is a collection of one or more network portals with a common portal group tag, which is an integer value. The default portal group tag is 1. All network portals must belong to a portal group even if there is only one portal in the group.

iSCSIInitiator

iSCSITarget

Host System Storage Device

Network Portal10.1.30.4

Network Portal10.1.30.21Port 3260

IP Network

CNS-000430

Storage Device

Network Portal10.1.30.21Port 3260

CNS-000431

iSCSITarget 1

iSCSITarget 2

iSCSIInitiator

Host System

Network Portal10.1.30.4

IP Network

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Portal groups are an advanced iSCSI feature used primarily for iSCSI session control. On a Celerra Network Server, you can manage portal groups as part of a target as shown in Figure 9 on page 79.

Figure 9 Three network portals in different portal groups

LUNs and LUN masksLUNs are linked to specific targets and are always identified in relation to the target. A target can have one or more attached LUNs. For identification, each LUN on a target is assigned a unique number in the range 0 through 255 (or 0 through 254 on Windows platforms) as shown in Figure 10 on page 79.

Figure 10 iSCSI targets with LUNs

After an initiator logs in to a target, the LUNs associated with the target appear as local SCSI disk devices on the host system. Using the SCSI protocol, the host system can configure and access the LUNs as standard SCSI disk devices.

Storage Device

Network Portal10.1.30.21Port 3260

CNS-000482

iSCSITarget 1

iSCSITarget 2

Network Portal10.1.30.7Port 3456

Network Portal10.1.30.28Port 3260

iSCSIInitiator

Host System

Network Portal10.1.30.4

IP Network

Portal Group 1Portal Group 1

Portal Group 4Portal Group 4

Storage Device CNS-000437

iSCSITarget 1

iSCSITarget 2

Network Portal10.1.30.21Port 3260

LUN 26

LUN 5

LUN 0

LUN 18

LUN 0

iSCSIInitiator

Host System

Network Portal10.1.30.4

IP Network

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LUN masks

In the iSCSI protocol, LUN masks control access to LUNs on targets. A LUN mask is a filter that controls which initiators have access to which LUNs on the target. If you create a LUN mask to deny an initiator access to a specific LUN, that initiator cannot see or access the LUN. Figure 11 on page 80 shows an example.

Figure 11 Effect of LUN masking

You define LUN masks on each target. To create a LUN mask, you identify the initiator by its IQN and specify to which LUNs the initiator is granted access.

!CAUTION!The iSCSI protocol supports locking on a block level (SCSI reservation) and not on a file level. Not every initiator takes advantage of SCSI reservation. Unless you are using Celerra iSCSI targets in a clustered environment, do not grant two initiators access to the same LUN. Granting multiple initiators access to the same LUN can cause conflicts when more than one initiator tries writing to the LUN. Simultaneous attempts to write to a LUN can cause corruption of the LUN.

Storage DeviceCNS-000483

iSCSITarget 1

iSCSITarget 2

LUN Maskiqn.1992-

05.com.abcgrant 18

LUN Maskiqn.1992-

05.com.abcgrant 0,26

NetworkPortal

LUN 26

LUN 5

LUN 0

LUN 18

LUN 0

Access to LUN allowed

Access to LUN blocked

iSCSIInitiator

Host System

Network Portal10.1.30.4

IP Network

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iSCSI namingEach initiator and target in an iSCSI network must be assigned a globally unique iSCSI identifier. A node’s iSCSI name is permanent for the lifetime of the node.

Because iSCSI nodes can share an IP address, the iSCSI name provides a way to identify an iSCSI node independently of the IP address. The iSCSI name is unrelated to the node’s IP address or MAC address—changing the IP address does not affect the iSCSI name.

A valid iSCSI name uses one of these formats:

◆ "iSCSI qualified name format" on page 81

◆ "Extended unique identifier format" on page 82

The iSCSI node name is typically assigned by the target or initiator. For example, when you create a target on the Celerra Network Server, the server can assign the target an iSCSI name in IQN format or you can specify an iSCSI name. Because the requirements for a unique, legal IQN or EUI name are stringent, you should accept the iSCSI name assigned by the server.

The server converts all uppercase characters in an IQN or EUI to lowercase characters.

iSCSI qualified name formatAn IQN is a globally unique identifier of as many as 223 characters. IQNs can contain only lowercase alphanumeric characters and the dot, dash, and colon characters—all other characters are invalid.

IQNs use the format:iqn.date.naming_authority:miscellaneous_string

where:

date = date when the naming authority’s domain name was issued. The date is in the form of yyyy-mm, including four digits for the year, a dash, and two digits for the month. The date must be a date during which the naming authority owned the domain name.

naming_authority = domain name of the naming authority for the node, with the elements of the domain name in reverse order (for example, com.emc for the domain name emc.com).

miscellaneous_string = alphanumeric string that uniquely identifies the node. The server generates this string based on the Celerra frame serial number.

IQN exampleFormat Date Miscellaneous string

Namingauthority

i q n . 1 9 9 2 - 0 5 . c o m . e m c : 0 0 0 1 8 7 9 4 0 2 8 1 0 0 0 0 - 2 9

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Extended unique identifier formatAn EUI is a globally unique identifier based on the IEEE EUI-64 naming standard. Names in this format consist of the prefix eui, a period, and a 16-character hexadecimal name. The hexadecimal characters represent the 24-bit company identifier assigned by IEEE and a 40-bit unique node identifier assigned by the company.

EUI example

iSCSI target aliasesBecause names in IQN or EUI format can be cryptic, the server supports aliases—a plain-language alternative to the formal iSCSI name for a target. An alias is an alphanumeric string of as many as 255 ASCII characters, or a maximum of 85 3-byte Unicode characters in UTF-8 encoding.

Because the alias is the key field in the server’s iSCSI databases, aliases must be unique for targets on a given Data Mover.

Aliases are used primarily by upper-layer applications. For example, when using CLI commands, such as server_iscsi, you can specify a target by its alias.

Format 16 hexadecimal characters

e u i . 0 2 f 0 4 d 6 7 a 4 2 5 e 7 8 a

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iSCSI discoveryBefore it can establish a session with a target, the initiator must discover where targets are located and the names of the targets available to it. To obtain this information, the initiator uses the iSCSI discovery process. The Celerra Network Server supports two types of iSCSI discovery:

◆ "SendTargets discovery" on page 83

◆ "iSNS discovery" on page 83

SendTargets discoveryIn SendTargets discovery, you manually configure the initiator with a target’s network portal (IP address and port number).

Figure 12 on page 83 shows how a target’s network portal is manually configured on the Microsoft iSCSI Initiator for SendTargets discovery.

Figure 12 Microsoft iSCSI Initiator (version 2.0) with network portal manually configured

The initiator uses that network portal to establish a discovery session with the iSCSI service on the target system. The initiator issues the SendTargets command to the iSCSI service on the target system. The iSCSI service responds with the names and addresses of all available targets on the system. For a Celerra Network Server, the target system is an individual Data Mover. SendTargets discovery does not discover targets on other Data Movers.

iSNS discoveryThe Internet Storage Name Service (iSNS) is a discovery and naming protocol that enables automated discovery of iSCSI devices in a TCP/IP network. With an available iSNS server, you can configure iSCSI initiators and targets to register themselves with the server. Then, when an initiator wants to discover accessible targets, it queries the iSNS server, which returns a list of available targets.

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The iSNS server maintains a database of information about iSCSI initiators, targets, portals, and portal groups. The iSNS server works with iSNS clients on the target systems. By configuring iSNS on a Data Mover, you create an iSNS client on the Data Mover. The iSNS client keeps a local database of all iSCSI components on the Data Mover.

Figure 13 on page 84 shows how the local database is published to the iSNS server and merged with the iSNS server database.

Figure 13 iSNS server database

The iSNS server uses Entity Status Inquiry (ESI) to monitor the availability of initiators and targets by querying the nodes on the network. Based on the results of the ESI queries, the iSNS server updates its database. If a node fails to respond to consecutive ESI queries, the iSNS server removes that node from its database.

The iSNS client on the Data Mover listens for ESI queries on a specific port. By default, the ESI port is dynamically selected for the Data Mover from the available ports, but you can assign a static ESI port.

iSCSI TargetClient

iSCSI InitiatorClient

iSNS Server

iSNS

iSNS

Key

iSNSDatabase

Portal

Initiator

TargetCNS-000435

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iSCSI authenticationAfter the initiator discovers the names and locations of targets, it can log in to the targets. iSCSI login typically consists of two stages:

◆ Security negotiation stage: The initiator and target determine if authentication is required, and if so, which type. With one-way authentication, the target authenticates the identity of the initiator. With two-way (or reverse) authentication, the initiator also authenticates the identity of the target.

◆ Operational stage: The initiator and target negotiate the operational parameters to be applied to the session.

CHAP authenticationFor authentication, the Celerra Network Server supports the Challenge Handshake Authentication Protocol (CHAP), which is the default authentication method for iSCSI.

CHAP provides a method for initiators and targets to authenticate each other through the exchange of a shared secret, which is typically a string of 12 to 128 random characters. (Microsoft supports CHAP secrets of 12 to 16 characters only.)

Because CHAP secrets are shared between the initiator and target, you must configure the same CHAP secret on both nodes.

The secret itself is not exchanged. A one-way hash function uses the MD5 algorithm to transform the secret into a unique value that cannot be changed back to its original form.

Typical one-way CHAP authentication consists of these actions:

1. The target sends a CHAP challenge message to the initiator.

2. Using the shared secret, the initiator calculates a value by using the hash function and returns the hash value to the target.

3. The target computes the expected hash value from the shared secret and compares that value to the value received from the initiator. If the values match, authentication is acknowledged and the login process moves into the operational stage. Otherwise, the target immediately terminates the connection.

If the initiator requires reverse CHAP authentication, the initiator also authenticates the target through the same procedure.

The initiator and target maintain databases of CHAP entries. A CHAP entry consists of the iSCSI name of a node and the associated secret.

Although you can configure a unique secret for each initiator-target pair, for reverse authentication, the server supports only one secret for each Data Mover. Similarly, the Microsoft iSCSI Initiator supports only one secret for each initiator.

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Index

AActivate Persist Through Power Loss 16, 34alert messages 68aliases, target 82application data, snapshot 13

modifying 61application label, snapshot 13APTPL 16, 34architecture, iSCSI 10AsyncEvent parameter 33asynchronous messages 16, 33authentication, iSCSI 85

Ccautions 5Celerra Manager 7CelerraCS application label 12CHAP 54, 85

authentication 15changing secrets 56creating entries 25deleting entries 57enabling/disabling authentication 54viewing entries 55

CLI (command line interface) 7comment text, snapshot 13concepts 10configuration guidelines 17configuring 20courses, EMC 73

Ddata associated with a snapshot 13data digests 31digests 15, 31discovery 16documents, related 9

EE-Lab 66EnableAptpl parameter 34Entity Status Inquiry (ESI) 24, 84error messages 68ESI 24, 84EUI 82event messages, asynchronous 16extended unique identifier 82extending a LUN 12, 14, 46

Ffile systems

creating and mounting 17

Gglossary 7groups, portal 78guidelines for configuration 17

Hheader digests 31

Iinitiators, iSCSI 75interface choices 7interoperability 66IQN 81iSCSI

aliases, target 82authentication 85characteristics on Celerra 11concepts 10controlling discovery responses 33discovery 83initiators 75, 77login statistics 37naming 81network portals 78nodes 77portal groups 78qualified names 81

iSCSI LUNs 11changing to read/write 44changing to read-only 43creating 21deleting 49deleting masks 53extending 12, 14, 46masks 51numbering 13properties 42read/write statistics 45

iSCSI servicedigest settings, viewing 32starting 26stopping 27

iSCSI targets 77aliases 82creating 20deleting 40listing 35network portals 39properties 36renaming 38

iSNS 10, 15changing configuration 29clearing configuration 30configuring 23status 28

Llabel, application 13

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Linux hosts, updating after LUN extension 48listing

LUN masks 51snapshots 58targets 35

login statistics 37logout messages, asynchronous 16, 33LUN masks

changing 52deleting 53

LUNs, iSCSI 11, 79creating 21deleting 49extending 12, 14, 46masks 14, 22, 51, 80numbering 13production 12properties 42read/write attribute 43, 44read/write statistics 45sizing 13snapshots 12virtually provisioned 11

Mmanaging

CHAP 54iSCSI LUNs 41iSCSI masks 51iSCSI service 27iSCSI targets 35snapshots of iSCSI LUNs 58

manuals, related 9masks, LUN 79

changing 52creating 22deleting 53listing 51managing 51

messages (error, alert, or status) 68mode, Windows-compatible 50MPIO 19Multipath I/O 19

Nnaming conventions, iSCSI 81network portals 39network topologies 76nodes, iSCSI 77

Pparameters, server

AsyncEvent 33EnableAptpl 34PreferDataDigest 31PreferHeaderDigest 31RequireChap 54, 70RequireDiscoveryChap 54, 71

SendTargetsMode 33WinCompat 50, 64

persistent reservation, SCSI 16APTPL option 34

planning 17PLU 12portals, network 78Powerlink 73PreferDataDigest parameter 31PreferHeaderDigest parameter 31production LUNs 12protocol, iSCSI 75

Rread/write attribute of LUN, changing 43, 44RequireChap parameter 54, 70RequireDiscoveryChap parameter 54, 71requirements, system 3restrictions 4reverse authentication 85

Ssecrets, CHAP 85SendTargets discovery 83SendTargetsMode parameter 33SLU 12snapshot LUNs 12snapshots

creating 60deleting 62demoting 65information about 59listing 58managing 58modifying application data 61promoting 64restoring 63

statistics, login 37status messages 68system requirements 3

Ttargets, iSCSI 77

aliases 82tasks

configuration 20management

CHAP 54iSCSI LUNs 41iSCSI masks 51iSCSI service 27iSCSI targets 35snapshots of iSCSI LUNs 58

terminology 7troubleshooting 66

Uuser interface 7

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Vvirtually provisioned LUNs 11, 21

Wwarnings 5website, EMC customer and partner 73WinCompat parameter 50, 64Windows hosts, updating after LUN extension 47Windows-compatible mode 50

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About this documentAs part of its effort to continuously improve and enhance the performance and capabilities of the Celerra Network Server product line, EMC periodically releases new versions of Celerra hardware and software. Therefore, some functions described in this document may not be supported by all versions of Celerra software or hardware presently in use. For the most up-to-date information on product features, see your product release notes. If your Celerra system does not offer a function described in this document, contact your EMC Customer Support Representative for a hardware upgrade or software update.

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