Dell EMC PowerVault MD 34XX/38XX Series Storage Arrays Administrator's Guide

Examples of typical use

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 disks 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.

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.