Dell PowerVault MD3200i - Manual (Page 13)

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Asynchronous Remote Replication
From RAID controller firmware version 07.84.44.60, MD Storage Replication Adapter (SRA) supports asynchronous
remote replication groups. This feature performs remote replication using Point-in-Time (PiT) snapshots and is
supported on both Fibre Channel and iSCSI MD storage arrays.
iSCSI-Based Remote Replication
With added support for Remote Replication over iSCSI protocol, greater replication distances are now possible.
However, this improvement in replication distances impacts latency (vs. previous Fibre Channel-only support).
Therefore, careful consideration should be taken during Datastore creation to ensure that only data that must be
replicated is included on the virtual disks you replicate. Once replication begins, closely observe the amount of data
being replicated and the time it takes to synchronize data. If the amount of time required to synchronize data is more
than the synchronization interval, a remote replication group becomes degraded and non-functional.
Proper sizing of your network infrastructure is a critical component of a successful disaster recovery solution. For more
information, see the following documentation:
• Dell PowerVault MD-Series Storage Arrays Administrator's Guide at dell.com/support/manuals.
• VMware Site Recovery Manager Documentation Center at vmware.com/support/pubs.
Support For Four Remote Replication Groups
SRA supports up to four Remote Replication groups per storage array. All protected Datastores must reside in one of the
four groups. Since a Remote Replication group is treated as a single entity, any action affecting the group (for example,
swapping roles) affects all virtual disks in the group. If cross-replication of Datastores is required (for example,
replicating from the recovery site to protected site), the Datastore virtual disks for the recovery site must be contained in
a separate Remote Replication group than the virtual disks on the protected site.
Impact Of 10-Minute Synchronization Interval
Remote replication groups require a 10-minute interval between automatic and manual synchronizations. If you request
a manual synchronization while a Remote Replication group is inside of a 10-minute synchronization interval, the manual
synchronization does not begin until the previous synchronization interval has passed. This may cause a delay in the
SRM workflow process which requires several synchronization operations to occur during test failover and/or failover
workflows. SRA is optimized to avoid requesting a manual synchronization if no changes are detected within the Remote
Replication group. However, if changes are detected, a synchronization is requested. The effect may be observed as a
lack of progress or slow progress through SRM workflows.
General Volume Recommendations
When designing a disaster recovery strategy using VMware Site Recovery Manager and MD Series storage arrays,
keep in mind these considerations:
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