Administrator Guide

Premium feature—Remote Replication
The following types of Remote Replication are supported on the MD storage array:
• Remote Replication — Standard asynchronous replication using point-in-time images to batch the resynchronization between the local
and remote site. This type of replication is supported on both Fibre Channel and iSCSI storage arrays (not between).
• Remote Replication (Legacy) — Synchronous (or full-write) replication that synchronizes local and remote site data in real-time. This
type of replication is supported on Fibre Channel storage arrays only.
Topics:
• About asynchronous Remote Replication
• Remote replicated pairs and replication repositories
• Types of Remote Replication
• Remote Replication requirements and restrictions
• Setting up Remote Replication
• Activating Remote Replication premium features
• Deactivating Remote Replication
• Remote Replication groups
• Replicated pairs
About asynchronous Remote Replication
Standard Remote Replication (asynchronous) is a premium feature that provides RAID controller-based data replication between a local
and remote storage array on a per-virtual disk basis. By identifying primary (local) and secondary (remote) virtual disk pairs, called
replicated pairs, write operations to the primary virtual disk of the pair are tracked by the RAID controller firmware and captured in a point-
in-time image and transferred to the secondary virtual disk in the pair.
Remote Replication groups allow you to manage synchronization of both virtual disks to create a consistent data set across local and
remote storage arrays. Point-in-time images on the primary virtual disk and the secondary virtual disk can be resynchronized in a batch
approach that increases replication throughput. When data synchronization completes, the system uses the point-in-time images on the
secondary virtual disk to ensure that the data is maintained in a consistent state during subsequent synchronization operations to the
secondary virtual disk.
NOTE: The standard Remote Replication premium feature is supported on both iSCSI and Fibre Channel storage arrays.
Remote replicated pairs and replication
repositories
Replicated pairs, comprising of a primary and secondary virtual disk, contain identical data copies as a result of data synchronization.
Replication repository virtual disks are used to manage replication data synchronization and are required for both the primary virtual disk
and secondary virtual disk in a replicated pair.
A replication repository consists of the following types of data:
• Resynchronization and recovery point images for both primary and secondary virtual disk.
• Log information that tracks regions on the primary virtual disk that is written between synchronization intervals. These logs are only
used on the primary virtual disk, but are also written to the secondary virtual disk in case of a role reversal.
• Statistics for each replicated pair.
The replication repository is normally created automatically when you create a replicated pair. However, you can also create the repository
manually.
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