Administrator Guide
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 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.
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.
Remote Replication requirements and restrictions
To use the standard Remote Replication premium feature, you must have:
• Two storage arrays with write access and both these storage arrays must have sufficient space to replicate data between them.
• Each storage must have a dual-controller Fibre Channel or iSCSI configuration (single-controller configurations are not supported).
• Fibre Channel Connection Requirements — You must attach dedicated remote replication ports to a Fibre Channel fabric
environment. In addition, these ports must support the Name Service.
• You can use a fabric configuration that is dedicated solely to the remote replication ports on each RAID controller module. In this case,
host systems can connect to the storage arrays using fabric.
• Fibre Channel Arbitrated Loop (FC-AL), or point-to-point configurations, are not supported for array-to-array communications.
• Maximum distance between the local site and remote site is 10 km (6.2 miles), using single-mode fibre Gigabit interface converters
(GBICs) and optical long-wave GBICs.
• iSCSI connection considerations:
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Premium feature—Remote Replication