Understanding SnapMirror

SnapMirror creates replicas of volumes hosting LUNs. SnapMirror mirrors a Snapshot copy of data on a source volume to one or more volumes configured as destinations of the source volume. SnapMirror can replicate a source volume to a destination volume on the same storage system or to a different storage system. When you use SnapMirror to replicate volumes from one storage system to another, the destination storage system can be in a different geographical location. This ability to duplicate data in different locations is a key component of a sound disaster recovery plan.

Data stored in a mirror on a destination volume can be accessed through SnapDrive. Because the mirror is volume wide, Snapshot copies of other data sets on the source volume are mirrored also.

SnapMirror updates the destination volumes to reflect incremental changes on the source volume. The result of this process is an online, read-only destination volume that contains the same data as the source at the time of the most recent update (using SnapManager Backup, in this case).

Attention
Because SnapManager uses SnapMirror in asynchronous mode, any disk writes that occurred on the source volume after the most recent SnapMirror replication update are not available if a catastrophic failure occurs before the next update. This is because they were not replicated to the SnapMirror destination volume.

Requirements for using SnapMirror with SnapManager

To use SnapMirror with SnapManager, you must have previously configured SnapMirror on both the source volume to be replicated and its destination volumes. How to complete these tasks is explained in your SnapDrive documentation. Your configuration must satisfy the following requirements:

There must be one or more SnapMirror source volumes hosting LUNs.
There must be one or more SnapMirror destination volumes for each source volume.
The size of the destination volumes must be equal to or greater than the size of the source volume.
SnapMirror licenses must be enabled on both the source and destination storage systems.
You must manually configure and initialize the SnapMirror replication between source and destination volumes.
You must disable the SnapMirror replication schedule on your storage system.
You must configure the SnapMirror replication as asynchronous.