Storage Fundamentals Network Topologies and Connectivity Options

© 2006 IBM Corporation

Storage Fundamentals

Network Topologies and Connectivity Options

Ulla Vest – [email protected] TMCC EuropeExecutive Briefing Centers

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Storage Fundamentals | Network Topologies & Connectivity Options | January 2007

Information Assets & SystemsThe Foundation for Information On Demand

Information Assets & Systems

Resource Virtualization

Systems Storage Servers Networking

Infrastructure Management

Business Continuity

Retention & Lifecycle

Management




Server and Storage Connectivity Options

Internal StorageDAS – Direct Attaced Storage

Block I/O

LAN(TCP/IP

Protocol)

LAN(TCP/IP

Protocol)File I/O

NAS – Network Attached Storage

iSCSI – SCSI over IP

Block I/O

LAN(TCP/IP

Protocol)

SAN – FC Storage Area Network

Block I/O

SAN (FC Protocol)




Dedicated Storage – Internal or Direct Attached

Distributed servers and storage - separate islands of information, separate storage management , storage/data ‘owned’ by one server

NetWare Windows

Linux

VMWare

Inefficient Use of Resources – more complex, higher Costs




Consolidated Storage

Ownership of storage resources is 'de-coupled' from servers Consolidated storage systems, storage management, enterprise data High agility and efficiency - reduced complexity, lower costs Supports highly available, scalable, disaster tolerant enterprise solutions

......

Consolidated Storage requires Network Approach




Reduced Cost through Networked Storage

$ per megabyte of user data 3-Year TCO

• Based on 2TB of user data Cost savings of SAN / NAS

driven by: • Improved disk utilisation

• Improved availability of enterprise information

• Tape drive consolidation

• Centralized management

0,84

0,38 0,35

DAS SAN NAS0

0,2

0,4

0,6

0,8

1

$ p

er

MB

of

Use

r D

ata

Source: Customer Interview, Expert Interview; McKinsey and MerrillLynch 2001




SAN - Storage Area Network (Fibre Channel based)

Servers ‘see’ local disks (or tape drives) SAN performs ‘Block I/O’: direct access to assumed disk sectors SCSI commands, filesystem-unspecific

SAN

consolidation

SCSI data!

SCSI data

Ethernet

Server view

=Fibre Channel

A dedicated Network Infrastructure for Data Traffic, designed for highest Performance, Availability, and Scale




What is Fibre Channel?

Common Transport System for multiple Protocols

SCSI-3 based serial interface technology enabling SANs• High bandwidth - 100-400MB/s per link, 3200MB/s ISL Trunking• Up to 10km link distance supported (more with extenders)• Large, scalable configurations, hot plugging, reconfiguration

Set of open standards for• Media and physical interfaces - copper or fiber optical• Data transmission, link services and signaling protocol• Mapping of upper level protocols different command sets• SCSI/FCP, HIPPI, ESCON, FICON, and also IP, IPI, ATM




SCSI Bus vs Fibrechannel

Serial line solves bit-desynchronisation (skew) problem

*80km with special materialFC receive FC send

Laser module

3 cm

SerializerOptic

al E

lect

ronic

s

SCSI bus Fibre serial10...80km*at 100 MB/s

FC-2:5...10kmat 200 MB/s

25m at 80 MB/s

Ultra160/320:12m at 160 MB/s5m at 320 MB/s

sender4 parallel wires

receiver

sender

receiver

receiver(RPQ 20km)




Fibre Channel – Why not TCP/IP?

Internet protocol (IP) is packet-oriented:• Each packet finds its own route through the network• Additional transmission control layer (TCP/IP) required; CPU load• Jams at high traffic rates

Fibrechannel is channel-oriented:• Packets are joined to sequences using one single route• Less routing overhead• Transmission control built-in, no CPU load




Fibre Channel Topologies

Point-to-Point• Direct connection • Full duplex operation

Loop• Shared loop - up to 127 nodes

• Shared bandwidth

• Half duplex operation

• Loop arbitration & loop initialization

Switched• Up to 16M nodes in a domain

• Allows multiple concurrent connections

• Full bandwidth between any two ports

• Full duplex operation

FC loop

Hub

Switch




Director

Loop protocol

Fabric protocol

Switch SwitchHubHub

Two HBAs in parallel plus multipathing software Two Loops in parallel, two switches in parallel or high

available, redundant core switches or directors

Mission Critical Topologies




Restricting Access with Zoning

Zoning is a switch feature to increase security and restrict access - zones can overlap and are based on WWN or port

Proper isolation of devices that do not support LUN masking

WWN = World Wide Name




FC SAN Benefits

Distance, performance & addressability Data is more accessible & more available More efficient use of storage resources Improved management of TBs of data Increased business flexibility Optimized enterprise backup procedures

Information used to belong to the server – now it belongs to the Enterprise

SAN

Fibre channel

Provides the flexible Infrastructure required for an on demand Storage Environment




IBM SAN Suppliers

Cisco MDS Multilayer Director / Fabric Switch

Family (IBM Resale)

R

IBM TotalStorage SAN b-type (Brocade OEM)

IBM TotalStorage m-type (McDATA OEM)

Portfolio Consolidation




Entry-level fabric switches

Mid-range fabric switches

Enterprise-class directors

R

R

R

Cisco MDS 9216i

IBM SAN32B-2 IBM SAN32M-2

IBM SAN140M / 256M

Cisco MDS 9506 / 9509 / 9513

IBM SAN256B

IBM System Storage SAN Family

IBM SAN64B-2

ÍBM SAN10Q-2IBM SAN16M-2IBM SAN16B-2 Cisco MDS 9020




NAS - Network Attached Storage

Clients 'see' file system NAS performs 'File I/O': file level acces Multiple network file access protocols, filesystem specific

NASAppliance

File protocolEthernet

NFS,CIFS,HTTP..

SAN Storage Server

NAS Gateway

An optimized IP Storage Device for File Sharing




Should I use SAN or NAS?

SAN if attaching databases or running applications that require "their" disksх NAS causes more CPU overhead (TCP) here and saturates transmission lines earlier (Ethernet)

NASif sharing files or working with user access rights (=file server)х SAN disk content typically cannot be shared, except in clusters

SAN with NAS Gateway accessif sharing files and running databases in one environment




iSCSI – SCSI over IP

SCSI commands encapsulated in TCP/IP Clients 'see' local disks (special software drivers required) iSCSI performs 'Block I/O': direct access to assumed disk sectors

Storage Area Network (SAN) over Ethernet

IP Storage Server

EthernetDisk protocol over IP

simulated local drives

iSCSI

SAN Storage Server

IP Gateway




iSCSI Target Fields

"Outside the datacenter"

Server islands without Fibrechannel access• Use iSCSI router to make SAN storage available to non-FC

servers

Where GB-Ethernet backbones exist• Consider a separate Ethernet "SAN" for high duty servers

For applications needing raw disk access• File-oriented applications are fine with NAS

• Applications optimized for disk access should use iSCSI




iSCSI comes – Fibrechannel goes?

iSCSI uses economic LAN technology No additional administrator skills (Fibrechannel) needed Integrated iSCSI adapters (e.g. Adaptec) IBM, Cisco, Microsoft, +... determination

Higher CPU & bandwidth overhead But: No CPU overhead when using iSCSI adapters Fibrechannel has still best network utilization at same clock rate Fewer supported clients (yet) Later technology, less gimmicks

PROs

CONs




Storage Networking Options

LAN(TCP/IP Protocol)

File I/O

NAS ‚Appliance‘

Block I/O

iSCSI ‚Appliance‘

SAN(FC Protocol)

Block I/O

Storage Pool

NAS Gateway

iSCSI Gateway

Documents

Storage Fundamentals Network Topologies and Connectivity Options