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    EMC Open Replicator for Symmetrix

    White Paper

    Platform-Independent Replication for Data Mobility, Remote Vaulting,

    and Data Migration

    Published January 2005

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    Copyright 2005 EMC Corporation. All rights reserved.

    EMC believes the information in this publication is accurate as of its publication date. The information is subject to

    change without notice.

    THE INFORMATION IN THIS PUBLICATION IS PROVIDED AS IS. EMC CORPORATION MAKES NO

    REPRESENTATIONS OR WARRANTIES OF ANY KIND WITH RESPECT TO THE INFORMATION IN THIS

    PUBLICATION, AND SPECIFICALLY DISCLAIMS IMPLIED WARRANTIES OF MERCHANTABILITY OR

    FITNESS FOR A PARTICULAR PURPOSE.

    Use, copying, and distribution of any EMC software described in this publication requires an applicable software

    license.

    EMC2, EMC, Symmetrix, Celerra, CLARiiON, CLARalert, Documentum, HighRoad, Legato, Navisphere, PowerPath,

    ResourcePak, SnapView/IP, SRDF, TimeFinder, VisualSAN, and where information lives are registered trademarks and

    EMC Automated Networked Storage, EMC ControlCenter, EMC Developers Program, EMC OnCourse, EMC Proven,

    EMC Snap, Access Logix, AutoAdvice, Automated Resource Manager, AutoSwap, AVALONidm, C-Clip, CelerraReplicator, Centera, CentraStar, CLARevent, Connectrix, CopyCross, CopyPoint, DatabaseXtender, Direct Matrix,

    Direct Matrix Architecture, EDM, E-Lab, Enginuity, FarPoint, FLARE, GeoSpan, InfoMover, MirrorView, NetWin,OnAlert, OpenScale, Powerlink, PowerVolume, RepliCare, SafeLine, SAN Architect, SAN Copy, SAN Manager,

    SDMS, SnapSure, SnapView, StorageScope, SupportMate, SymmAPI, SymmEnabler, Symmetrix DMX, Universal

    Data Tone, and VisualSRM are trademarks of EMC Corporation. All other trademarks used herein are the property of

    their respective owners.

    Part Number H1459

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    Table of Contents

    Intended Audience ............................................................................................. 4

    Execut ive Summary ........................................................................................... 4

    Open Replicator Modes of Operation ............................................................... 4BCV Mode.................................................................................................................................... 5

    Live Mode..................................................................................................................................... 5

    Appl ications for Open Replicator ..................................................................... 6

    Data Mobility ................................................................................................................................ 6

    Data Vaulting................................................................................................................................ 6

    Migration ...................................................................................................................................... 7

    Open Replicator Architecture............................................................................ 7

    Change Tracking, Protection, and Update................................................................................... 8

    The Track Change Process BCV Mode Operations ................................................................. 8

    Incremental Updates for Push Operations................................................................................... 8Live Push Operations................................................................................................................... 8

    Live Pull Mode (Data Migration)................................................................................................... 9

    Pull Mode Deferred Copy Quality of Service Parameter.................................................... 9Pace (Throttle) Control Quality of Service Control Parameter .............................................. 9

    Open Replicator Data Movement............................................................................................... 10

    Scaling, Management, and Platform Support ............................................................................ 10

    Open Replicator and Data Consistency..................................................................................... 11

    Similarities and Differences with SRDF Family Replication....................................................... 11

    Summary.................................................................................................................................... 12

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    Intended AudienceThis white paper is intended for EMC customers, systems integrators, systems administrators, and the members of theEMC and partners professional services community, as well as anyone interested in learning more about EMCOpen

    Replicator for Symmetrix. It is assumed that the audience is familiar with SymmetrixDMX storage systems and

    existing platform software products such as the SRDFand TimeFinderfamilies of remote and local replicationproducts. Open Replicator is software for Symmetrix DMX systems running Enginuity 5x71 and beyond. Open

    Replicator is supported in open systems environments, supporting fixed block architecture (FBA) devices. Mainframe

    or CKD devices are not supported at this time.

    Executive SummaryEMC Open Replicator for Symmetrix enables remote point-in-time copies to be used for high-speed data mobility,remote vaulting, migration, and distribution between EMC Symmetrix DMX and qualified storage systems such as the

    CLARiiONCX series offeringwith full or incremental copy capabilities. And because it leverages the high-end

    Symmetrix storage architecture, Open Replicator offers unmatched deployment flexibility and massive scalabilityso

    users can meet mixed service-level requirements with minimal operational impact.

    Rapidly copy data between Symmetrix, CLARiiON, and third-party arrays

    Perform online migrations from qualified storage to Symmetrix DMX with minimal disruption to hostapplications

    Push any live source Symmetrix DMX volume to a target volume on qualified storage with incrementalupdates

    Copy from source volumes on qualified remote arrays to a Symmetrix DMX volume

    Organizations are under pressure to protect critical data beyond simply creating backup tapes. This includes creating

    more-frequent local replicas, such as full-volume copies and snapshots, as well as making sure data is available atremote locations for a variety of uses. In most cases the operational requirements of the business will dictate the type of

    remote replication required. These operational requirements may consist of recovery point objectives (amount of data

    exposure), recovery time objective (how long it takes to restart), bandwidth (what type is available, how much is

    required, and at what cost), distance between sites (speed of light delays), and impact on production applications.

    Open Replicator is tightly integrated with the EMC TimeFinder and SRDF families of local and remote replicationsolutions, providing enterprises with highly flexible and lower-cost options for remote protection and migration. Its

    ideal for applications and environments where economics and infrastructure flexibility outweigh RPO and RTOrequirements.

    Protect lower-tier applications at remote locations more cost effectively and flexibly

    Reduce TCO by pushing or pulling data from Symmetrix DMX systems to other qualified storage arrays inconventional SAN/WAN environments

    Create remote point-in-time copies of local production volumes for many purposesfrom data vaulting toremote testing and development

    Get cost-effective application restore capabilities with minimal RPO/RTO impact

    Enable compliance with industry policies and government mandates through efficient data replication

    Open Replicator Modes of OperationOpen Replicator is designed as a data mobility product to copy point-in-time images between a Symmetrix DMX

    platform and any qualified storage platform over traditional SAN infrastructures and protocols. While the software runson a Symmetrix DMX platform, it can copy data from, and send data to, other supported storage systems on the SAN.

    Open Replicator can push copies out to other arrays or it can pull copies in from other arrays. It is important to

    remember that unlike continuously updated remote replication technologies such as the SRDF family, Open Replicator

    replicas are always point-in-time copies, representing the data state at a particular instance.

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    BCV ModeOpen Replicator pushes and pulls volume copies in two different modes. First, it can run in BCV, or static mode.

    This means that the DMX resident volume continues to service host application I/Os while a split TimeFinder/Mirror or

    TimeFinder/Clone BCV is used as the source. If it is known that a particular volume will not be accessed by a hostapplication, it can also be used as the source, without a BCV.

    Point-in-Time Volume Pull

    Target

    Target

    Target

    STD

    STD

    STD

    Point-in-Time BCV Push

    STD

    BCV

    Target

    Target

    Target

    When pushing a static volume to another array, Open Replicator can support moving/copying up to 16 remotecopies of the local static volume

    In BCV pull mode, a full copy of the remote volume is copied to a static DMX volume

    Live ModeOpen Replicator also supports a live mode for both push and pull operations. In live mode, host I/O to and from the

    DMX volume is permitted while the copy process continues in the background. The copy is still at a point in time,

    representing the data state when the copy command was issued, but

    production I/O can continue and no BCV is required.

    In live push mode, the background copy to the remote array begins

    when the session is activated. If a local write comes in from a host

    before a specific track has been copied off to a remote system, thetarget track is immediately copied to the remote system before the

    local write is permitted. Once a track has been copied and the track

    protection cleared, no further write delays would occur.

    The I/O completion delay can result in a slight latency for the local

    I/O until the track has been copied to the remote array so the physical

    distance between arrays is limited to synchronous replication lengths.

    Also with live push, a point-in-time copy of one source volume canbe created to one target location, with the ability to incrementally update it at any time. So the benefit of live push

    mode versus BCV push mode is the economics of not requiring disk

    space for a local copy, but latency, distance, and copy quantityrequirements must be within the limitations before deploying.

    Point-in-Time Live Push

    STD Target

    Start: 6:00 am

    End: 6:02 amImage: 6:00 am

    Live Data Migration Pull

    STD

    STD

    Old

    Old

    In both BCV and live push modes the remote storage volumes mustbe kept offline to host access so no remote volume changes occur if it

    is desired to maintain the ability to perform incremental updates

    during future push operations on the same volume. If host access to

    remote data is required, EMC recommends using local point-in-time

    copies (or a second copy created using Open Replicator).

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    Open Replicator can also pull volumes from other arrays in live mode. This can be extremely useful for migrations and

    when restoring vaulted data from a remote location. For live pulls, host I/O can begin against the empty volume in

    the Symmetrix DMX as soon as the copy process is started. If the host requests data which has not yet been copied

    from the remote array, Open Replicator will immediately prioritize and copy the requested information to fulfill the host

    request. While there will be a minimal time delay to get the data from the remote storage platform if it has not alreadybeen copied over, this feature allows you to immediately begin to use the DMX volumes without having to wait for the

    copy process to complete.

    All pull operations must be full volume copies because Open Replicator cannot track changes to related volumes located

    on other storage systems.

    Applications for Open ReplicatorOpen Replicator is extremely well suited to a number

    of applications where requirements exist to move andcopy point-in-time copies between a Symmetrix

    DMX system and other EMC and non-EMC storage

    platforms. In particular, Open Replicator meets

    customer demands for data mobility, remote vaultingand data migration.

    Data MobilityData mobility is greatly enhanced through the use of

    Open Replicator. By using a local point-in-time

    copy on the Symmetrix, such as a TimeFinder/Mirror

    or TimeFinder/Clone BCV, customers have theoption of pushing up to 16 copies of a source volume

    out to supported storage arrays.

    This is useful for content distribution such aspushing file systems out to additional or multiple

    mirror sites, or updating remote offices. Because

    Open Replicator supports data mobility from Symmetrix to other qualified arrays, customers can better match their costto the required service level. For instance, if it is necessary to push an application volume to many remote offices for

    concurrent use, those offices may be able to use a CLARiiON CX300 array versus a Symmetrix DMX in each location

    to more appropriately balance their service level requirements.

    SAN

    STD

    BCV

    Open Replicator for Symmetrix

    High-Speed Data Mobilit y

    SANSAN

    STD

    BCV

    Open Replicator for Symmetrix

    High-Speed Data Mobilit y

    Data VaultingData vaulting, the practice of storing a

    set of point-in-time copies at a remotelocation in the event of primary site

    data loss, is extremely well suited to

    Open Replicator. Copies of production

    volumes can be copied back to eitherthe primary site or to an alternative site

    for business continuity purposes asrequired by the response to a particulardisruption.

    Here, volumes are copied to a tier 2

    storage device at either a local or a

    remote location. In the event of aprimary site failure, the volumes could

    be copied back to the primary array

    using live pull mode (outlined in the next section), which would allow immediate host access even while the copy is

    Open Replicator for Symmetrix

    Using Tier storage for vaulting Create a BCV from the

    standard

    Production never stops on thestandard Push initial copy to remote

    location at 12PM

    Update changes and Push

    incremental updates offsite to

    vault at 6AM

    Point in Time Remote Vaulting

    BCVSTD

    6:00 Tier-2

    Storage

    ExtendedSAN

    Open Replicator for Symmetrix

    Using Tier storage for vaulting Create a BCV from the

    standard

    Production never stops on thestandard Push initial copy to remote

    location at 12PM

    Update changes and Push

    incremental updates offsite to

    vault at 6AM

    Point in Time Remote Vaulting

    BCVSTD

    6:00 Tier-2

    Storage

    ExtendedSAN

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    completing, or the data could be copied back to a replacement DMX array in another facility if necessary, again using

    live migration or even BCV copy modes.

    Tier 2 storage typically has lower functionality and lower performance than tier 1, and the layout of the data is

    optimized for high-density storage rather than high-performance application access. So while the benefit versus using

    traditional high end replication between like arrays is cost savings, data vaults are usually not well suited to use for

    hosting application restart or for subsequent rapid fail back. Rather, the data volumes would be copied to anotherstorage system in order to resume production operations.

    MigrationOne of the most painful parts of

    implementing new storage

    technologies can be migrating datafrom existing storage systems to

    new storage systems. Typically

    this can be a very disruptiveprocess requiring a considerable

    amount of application downtime.

    First, applications need to be

    brought down, then backups made,then the backups would berestored to the new storage,

    verified, tested, and finally the

    applications could be restarted onthe new storage platform.

    Open Replicator for Symmetrix

    Symmetrix DMX installed between

    hosts and original storage

    Data migration occurs while

    application remain online

    Host I/Os pass through Symmetrix

    When all data is migrated, unplug and

    remove original storage

    High-Speed Online Data Migration

    Open Replicator for Symmetrix

    Symmetrix DMX installed between

    hosts and original storage

    Data migration occurs while

    application remain online

    Host I/Os pass through Symmetrix

    When all data is migrated, unplug and

    remove original storage

    High-Speed Online Data Migration

    If the migration were between Symmetrix systems which support SRDF/S, then the issues become much simpler. Thenew storage can be installed and configured to support the new volumes, SRDF/S can be brought up to mirror the data

    in real time, and the hosts could be cut over to the new storage at any point in time that is convenient for the

    applications.

    If however, the donor systems are non-Symmetrix storage arrays, then Open Replicator can be used to achieve much the

    same effect. To migrate to a DMX system using Open Replicator, first the new DMX system would be installed andconfigured to support the host applications. Open Replicator would then be configured to establish a live pull of all of

    the remote volumes to the new DMX system. At this point the hosts would be reconfigured to read and write to the

    DMX system. Once Open Replicator begins the copy sessions, host applications could be brought back up and operatenormally, albeit at a degraded rate, until all of the data was copied over to the Symmetrix. Once the data copy is

    complete, merely disconnect the donor storage and roll it out the door.

    While Open Replicator could be configured to move point-in-time copies from one non-DMX platform to another, this

    would not be the optimal use for this product since local storage must be configured to stage the copies between the pull

    and push operations. There are other configurations for Open Replicator, such as single and multi-hop repetitive

    replication solutions, which are possible but which arent covered in this paper.

    Open Replicator ArchitectureOpen Replicator runs as part of the Enginuity operating environment (5x71 or later) on the Symmetrix DMX storage

    platform. Specifically, Open Replicator is implemented on the front-end FA directors of the Symmetrix system.

    (SRDF family products run on back-end directors.)

    This means that Open Replicator I/O is handled through the same types of FA ports that hosts will use to connect to theDMX array. Any Fibre Channel SAN infrastructure components approved for DMX connectivity will be supported

    with Open Replicator. No unique protocols or protocol extensions are required by Open Replicator. To remote storage

    arrays, Open Replicator ports will appear to be generic host connections. From a protocol perspective, Open Replicator

    enables the FA ports to act as initiators as well as targets on the SAN.

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    Change Tracking, Protection, and UpdateInternally on the DMX platform, changes to DMX devices are tracked in much the same manner as they are forTimeFinder and SRDF family replication operations, using Symmetrix Differential Data Facility (SDDF) track tables.

    By using track tables, minimal cache is required to track changes and keep volumes in synch with each other; no side

    files or temporary storage is required.

    A primary difference between Open Replicator and SRDF family operations is that Open Replicator only keeps track ofwhich tracks on the local DMX volume have changed, and which are owed to the remote storage volumes while SRDF

    family products maintain this relationship on all storage systems and volumes participating in the replication

    relationship. Open Replicator always assumes that no changes have been made to the remote volume.

    These track tables partition a Symmetrix device into uniformly sized segments, each represented by a bit in a bitmap.

    Each time a change is made to a source volume, the volumes track tables would be updated to indicate in which trackthe change occurred.

    The Track Change Process BCV Mode OperationsIn the case of BCV mode, separate SDDF sessions track the changes between the production volume and the BCV

    volume (normal TimeFinder Family change tracking), and between the BCV volume and the remote array volume.Upon creation of an Open Replicator operation, two bitmaps get set up for the DMX BCV (the Open Replicator

    controlling volume) and remote volume relationship. Of course, the BCV will also have a track table relationship with

    its source (the production volume) that is handled in much the same way. The Protection Bitmap indicates whether ornot a track is owed to the remote copy.

    At initial activation, all tracks need to be copied to or from the remote volume, so all tracks would still be protected. Aseach track gets copied the protection bit is cleared and the track becomes unprotected. (It is no longer owed to the

    copy, so normal I/O can proceed.)

    Upon completion of the track copy process, the copy is complete, and the BCV can be re-established and split from its

    source. If, while this is occurring, the host writes to a track on the Symmetrix device, the corresponding bit in the

    SDDF bitmap is changed to indicate which tracks need to be updated in order to perform an incremental update.

    Incremental Updates for Push OperationsWhen the recreate / activate commands are issued the SDDF bitmap gets copied to the protection bitmap and the SDDF

    bits are zeroed out. With a new protection bitmap in place, those tracks which are protected (i.e., the changes since last

    time) can now be sent to the target volumes. Again, as in the case of the original copy process, once a protected track iscopied to the target volume, the protection bitmap is cleared. When all protection bits have been cleared, the

    incremental update process is complete and the BCV is ready for another re-establish and split from its source; enabling

    yet another set of incremental updates.

    Live Push OperationsIn Live Push mode, no separate BCV is involved in the replication process. All operations are executed against thesource volume as live I/O is performed against the source volume. To make this possible, a special mechanism must be

    employed to ensure that the existing point in time data is copied to the remote array prior to a new write being allowed

    to that track. A Copy on First Write function will ensure that a protected track is cleared and copied to the remotearray before a local write to that track is permitted and the protection bit is cleared.

    At the point of activation, the SDDF bitmap for the source session is zeroed out, and the protection bitmap is all 1s.

    Unlike the case of BCV mode, however, the protection bitmap has extra significance in that a new write will not be

    permitted to disk until the protection bit is cleared. As the copy process proceeds, protection bits are cleared. If a newwrite arrives for an unprotected track (that data has already been copied), then the write proceeds normally. If the

    protection bit is still set, the write is held until the track is copied and the bit is cleared.

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    This can result in a slight latency for writes to a protected track during Live Push mode operations. Once the protection

    bit is cleared, either through the copy on first write operation or the normal background copy operation, no further

    delays would be encountered. This is not an issue during a BCV mode push since the BCV would be separated from

    the production application and would not be receiving any local writes.

    Live Pull Mode (Data Migration)

    For Live Pull operations, the local DMX volumes can be accessed by the hosts as soon as the process is activated, eventhough there may be no data in much of the DMX volume at the time of activation. A process called Copy on FirstAccess is employed to make sure that data is available to a host operation when it is needed.

    First, the DMX will create protection and SDDF bitmap sessions for the copy process. All bits in the protection bitmapare marked 1. As the background copy process proceeds, the protection bits get cleared when the data for that track

    has been received by the DMX system. If the host requests access (read or write) to data that has had its protection bit

    cleared, it will receive the data contained in the DMX volume.

    If the host attempts to access a track that is still protected, the Open Replicator process will prioritize the fetch of that

    track from the donor volume, so it is the next track copied. Once it is received, the protection bit is cleared and the host

    operation is serviced. As in the case of writing to a protected track on a live push, accessing a protected track during a

    live pull will impose a small amount of latency as the data is fetched from the remote array. The amount of latency will

    be directly related to the circuit distance between the source and target as well as the availability of bandwidth to servicethe copy traffic.

    Pull Mode Deferred Copy Quality of Service Parameter

    Within the Pull mode process are two modes, deferred copymode and copymode; dynamic switching between the two

    modes is a key feature of Open Replicator

    Deferred copymode is a state during which all background copy activity from the remote array is suspended; only

    tracks accessed from the local hosts are copied over to the local DMX volumes. In deferred copy mode for example, a

    local read or write could still be executed against a track on the DMX which is still protected since the copy on first

    access process will still perform the read from the remote volume to satisfy the local I/O. What wont be occurring isthe background tasks of copying tracks and clearing protection bits.

    Copy mode engages the background copy and is the normal mode of operation to complete the copy process.

    Deferred mode has several advantages. For example, there is far less demand on DMX and SAN resources, so

    switching into deferred mode during periods of peak activity can help reduce any performance impacts which may be

    felt during copy operations. Also, it allows the copy session to be configured, activiated, and tested at any time withouthaving to worry about when the bulk of the copy is to be scheduled.

    Pace (Throttle) Control Quality of Service Control Parameter

    Open Replicator supports an optional parameter, called Pace a value between 0 and 9, which will impose an artificial

    latency between each Open Replicator I/O. The latency imposed can be set between 0 (Pace=0) and 600 ms (Pace=9).Setting a higher Pace parameter will lower the resource utilization rate for Open Replicator processes and extend the

    time it takes to complete a copy operation.

    Adjusting the Pace parameter can help balance out the port utilization between Open Replicator and other applicationI/O that may be using the same ports. In cases where application performance is a higher priority than the speed at

    which Open Replicator completes its copy assignments, setting the Pace parameter higher can help application response

    times during periods of heavy use. Please refer to the Open Replicator CLI Command Reference manual for

    information on setting the Pace parameter.

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    Open Replicator Data MovementOpen Replicator uses standard Symmetrix devices and remote storage array devices presented on Fibre Channel ports,

    as identified in most cases by WWNs, as the objects of the data movement. (On Symmetrix systems, Symmetrix device

    IDs may be used in place of WWNs.) It creates a full, track by track copy of the source device to the destinationdevice. Incremental updates are also handles at the Symmetrix track level.

    The following conditions apply in all cases:

    Target devices should be at least as large, or larger, as source devices. When copying to larger devices, LUNexpansion is left to native host utilities. Open Replicator does not provide file system or volume managementextension capabilities.

    o For operations where return copy to the original source device is an important requirement, care mustbe taken to assure that the source and target volumes are the exact same size since it will not be

    possible to copy to a smaller volume, even if it is only 1 KB different. It will always be possible to

    copy back to a different device than the source however.

    o It may not be possible to exactly match the device sizes between arrays. In this case, the target devicemay be configured slightly larger than the source device. In order to subsequently pull data back to

    the orginal source device, the -force_copy option has been provided to allow Open Replicator to pull

    data from the larger device. You should never use this option if the target device has beenreconfigured on the host to use more storage than the original source device. Expanding a LUN with

    the diskpart utility on Windows hosts would be an example of such a reconfiguration. Data loss and

    corruption will occur if actual data is truncated as a result of copy from a larger device to a smallerone.

    For BCV mode push, the primary DMX volume can be the standard device (if all host I/O is quiesced). If hostI/O will not be suspended, then either a TimeFinder/Mirror BCV or a TimeFinder/Clone BCV may be used as

    the Open Replicator source volume. TimeFinder/Snap BCVs are not supported at this time.

    All pull operations must be full copy. No incremental pull capability is currently supported.

    In all cases, the target devices represent a single discreet point-in-time copy of the source. Although recurringcycles can be scripted at set time intervals, no continuous updates in any mode are supported.

    Live Pull operations do not mirror any host writes back to the donor array devices. The remote donor volumesexist as gold copies at all times (assuming no local host access).

    Copies are at the binary level and cannot transcend host operating system incompatibilities or file system andvolume manager issues. Compatibility is assured only in cases where like O/S, file systems, and volume

    mangers are used to access the target volumes.

    Best practices should include maintaining point-in-time copies of remote volumes where local host access isnecessary. This will maintain the ability to continue to push incrementally, as well as maintain a good copy ofdata during push operations.

    Scaling, Management, and Platform Support

    Open Replicator supports up to 128 concurrent push or pull sessions at any one time. Each Open Replicator sourcevolume is counted as a session. In the case of a BCV mode push, up to 16 copies of the source volume can be pushed

    out to remote storage platforms in a single session. Therefore, a single Symmetrix DMX can theoretically push

    volumes to up to 2048 remote systems. And as long as the 128 concurrent session limit is not exceeded, sessions can beserialized in order to copy more than 128 DMX volumes to or from remote arrays. Further, all modes of Open

    Replicator can be used concurrently as long as the 128 session limit is not exceeded.

    Open Replicator is supported at both the SymmAPI and SymCLI levels. Full CLI command support is provided

    through Solutions Enabler 6.0 and higher. Open Replicator requires SAN connectivity from selected DMX FA ports to

    ports on the remote storage array. SAN configuration and LUN masking is not managed by Open Replicator.

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    Open Replicator runs on Symmetrix DMX platforms running Enginuity 5671 or later with Solutions Enabler 6.0 or

    later. The current list of platforms that Open Replicator can copy to and from can be found on the EMC Support

    Matrix. (See EMC.com.) At GA, Open Replicator will support all Symmetrix systems with Fibre Channel directors and

    all CLARiiON systems with Fibre Channel front-end ports. Non-EMC storage arrays will be supported as E-Lab

    qualifications complete; check the EMC Support Matrix for the latest list.

    Open Replicator and Data ConsistencyLocalized data consistency across a group of Symmetrix DMX source volumes can be achieved in two ways with Open

    Replicator.

    First, when using TimeFinder/Mirror or TimeFinder/Clone BCVs as the source volumes, TimeFinder/CG can be used tocreate a consistent set of point-in-time images across any number of source volumes. Secondly, it is possible to use

    Enginuity Consistency Assist (ECA) when creating a set of live push images; all volumes in the set would be created at

    the same logical point in time assuring restartability of the remote data sets.

    While TimeFinder-style consistency groups are supported, there is no analogous support for SRDF-style consistency

    groups. This means that Open Replicator, unlike the SRDF product set, cannot guarantee consistency at the target. For

    example, if a live push command was issued against 25 volumes in a set, and some of those could not reach theirdestination because of SAN connectivity issues, there is no means of stopping the replication of the other volumes at the

    exact same time. The result could be an incomplete set of volumes at on remote storage systems. If this were a criticalcomponent to the application environment, EMC recommends creating point-in-time copies on the remote arrays until

    the all of the volumes in the Open Replicator set are copied or updated.

    Similarities and Differences with SRDF Family ReplicationIt is easy to see some similarities between the Open Replicator capabilities and those of SRDF/S and SRDF/A,

    especially when you want to copy data to a remote storage system for the purposes of data protection.

    Open Replicator for Symmetrix

    Replicate between Symmetrix DMX

    and other EMC/non-EMC systems

    Provides point-in-time remote

    vaulting

    Applications can be restored to an

    alternate systems and restarted

    Consistency created on sourceSymmetrix DMX, no guaranteed

    group delivery when copied to

    target

    Symmetrix Remote Data Facility

    Replicate between Symmetrix

    source and target systems

    Provides continuous remote data

    protection

    Applications can be restarted from

    target system

    Full Consistency Group supportacross multiple volumes and across

    multiple Symmetrix systems

    Comparing Open Replicator to Symmetrix Remote Data Facility

    Open Replicator for Symmetrix

    Replicate between Symmetrix DMX

    and other EMC/non-EMC systems

    Provides point-in-time remote

    vaulting

    Applications can be restored to an

    alternate systems and restarted

    Consistency created on sourceSymmetrix DMX, no guaranteed

    group delivery when copied to

    target

    Symmetrix Remote Data Facility

    Replicate between Symmetrix

    source and target systems

    Provides continuous remote data

    protection

    Applications can be restarted from

    target system

    Full Consistency Group supportacross multiple volumes and across

    multiple Symmetrix systems

    Comparing Open Replicator to Symmetrix Remote Data Facility

    There are key differences however. The SRDF family of remote replication solutions provides the most advanced and

    resilient continuous remote replication capabilities on the market. In addition, SRDF/S and SRDF/A (with or withoutthe added benefit of SRDF/Consistency Groups) provide the key ability to restart applications at the remote recovery

    site, and then incrementally fail back when the primary site returns to product state. Open Replicator, on the other hand,

    enables the creation of remote point-in-time copies, typically on second tier storage optimized for storage density overperformance considerations. . These second tier storage platforms are typically configured for low access storage and

    not application execution,

    making them unsuitable tothe task.

    When to use each should be a

    decision based upon an

    evaluation of service levels(performance, availability,

    functionality, and economics)

    required for each application

    or business. That said, a keybenefit to Symmetrix DMX is

    that all of the solutions can be

    running in parallel, with eachapplication getting the

    solution that best fits its

    service level requirements.

    EMC Open Replicator for Symmetrix 11

  • 8/12/2019 Emc Open Rep Symm

    12/12

    SummaryIn todays ever-changing business environment, it is imperative to be able to copy and move data to where it will

    provide the most value to your organization. In fact, the more flexibly and efficiently data can be moved, the more

    adaptable an IT infrastructure can become, enabling organizations to better match the cost of their environment to the

    value of their various information sets.

    Consolidation and distribution of data can be slow and inconsistent, dependent on hosts, and disruptive to existing

    networks and applications. Centralizing data for maintenance or critical business processes can be challenging,especially in an environment with multiple distributed locations that have different vendors storage arrays. Or consider

    an organization with software developers in multiple locations or even departments. It is extremely resource and

    time-intensive to supply the freshest production data for the software developers testing efforts.

    Now EMC makes consolidation and distribution easier for organizations by enabling data mobility, vaulting, and

    migration solutions with Open Replicator. Imagine being able to move terabytes-per-hour safely within a SAN,

    between Symmetrix and CLARiiON storage systems, and even between EMC and other vendors storage arrays. OpenReplicator for Symmetrix delivers on this need.

    Visit www.emc.comor contact your local EMC sales representative for more information.

    EMC Open Replicator for Symmetrix 12

    http://www.emc.com/http://www.emc.com/