Dell POWERVAULT MD3600I - Manual (Page 186)

Types Of Remote Replication
The following are the types of Remote Replication premium features supported on your storage array:
• Remote Replication — Also known as standard or asynchronous, it is supported on both iSCSI- and Fibre
Channel-based storage arrays (both local and remote storage arrays must use the same data protocol) and
requires a dual RAID controller configuration.
• Remote Replication (Legacy) — Also known as synchronous or full-write, it is supported on Fibre Channel
storage arrays only.
Differences Between Remote Replication Features
As compared to the (synchronous) Remote Replication (Legacy) feature, the standard (asynchronous write) Remote
Replication premium feature uses a point-in-time snapshot image to capture the state of the source virtual disk and only
writes data that has changed since the last point-in-time image.
With standard Remote Replication, the remote storage array is not fully synchronized with the local storage array. As a
result, in the event of a sudden, total loss of the remote storage array, some transactions could be lost.
With synchronous Remote Replication (Legacy), every data write to a source virtual disk is replicated to a remote virtual
disk. This produces an identical, real-time remote of production data.
Other differences include:
• Number of repository virtual disk required — Standard Remote Replication requires a repository virtual disk to
be created for each replicated pair (remote virtual disk-to-local virtual disk). Alternately, Remote Replication
(Legacy) only requires a single repository virtual disk.
• Data protocol supported — Standard Remote Replication is supported on both iSCSI and Fibre Channel storage
arrays. Remote Replication (Legacy) is supported only on Fibre Channel storage arrays.
NOTE: Both remote and local storage arrays must be of the same data protocol -- replication between
Fibre Channel and iSCSI storage arrays is not supported.
• Distance limitations — Distance between local and remote storage arrays is unlimited using the Standard
Remote Replication premium feature. Remote Replication (Legacy) has a limitation of approximately 10 km (6.2
miles) between local and remote storage arrays, based on general latency and application performance
requirements.
Examples Of Typical Use
Standard (asynchronous) Remote Replication is more network-efficient and generally more suitable in environments that
require fast, non-stop processing. Remote backup consolidation, long-distance disaster recovery and 24 x 7 data
protection are also common uses.
Synchronous Remote Replication (Legacy) is designed to provide replication between a relatively small number of local
systems that require business continuity — for example, data center-type operations, local disaster recovery and other
top-tier applications.
Upgrading To Asynchronous Remote Replication From Remote Replication (Legacy)
When you upgrade a RAID controller firmware version that supports both legacy and non-legacy Remote Replication
premium features, all legacy Remote Replication configurations in the RAID controller remain unaffected and continue
to function normally.
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