How SnapManager uses SnapMirror

When SnapMirror updates occur

If Exchange data backed up by SnapManager resides in a volume that is configured as a SnapMirror source volume with one or more appropriately configured destination volumes, a SnapManager backup of an Exchange database stored on that volume causes SnapDrive to request a SnapMirror update for that volume. The schedule you define for backups sets the schedule for mirror replication.

SnapMirror replication type

When you use SnapMirror to replicate SnapManager backups, SnapMirror replication is asynchronous. This means that changes made between SnapManager backups are not reflected in the SnapMirror target volume, and any restore from the target volume would restore the databases to their state at the time of the last SnapManager backup. However, you can use SnapDrive to minimize the time between SnapMirror replications.

For more information about scheduling your SnapMirror replications, see Scheduling SnapMirror replication for SnapManager backups.

SnapMirror replication unit

When you use SnapMirror to replicate SnapManager backups, you can replicate only volumes, not qtrees. SnapMirror qtree replication is not supported by SnapManager.

How SnapMirror replication works

In previous releases of SnapManager for Microsoft Exchange, the SnapMirror mirror update was always initiated for each Snapshot copy as it was taken. This approach resulted in redundant mirror updates. With SnapManager 3.0 for Microsoft Exchange and later, the mirror update request is delayed until SnapManager explicitly requests it, after the SnapManager backup is complete.

Note
If you do not want the SnapMirror destination volume to be updated after a backup is taken, you can override the update using the Backup Wizard or the Backup tab.

The following table provides an overview of how SnapMirror destination replication works.

Stage	Process
1	Configure SnapMirror relationship between source volumes and destination volumes. Create a Custom schedule with schedule parameters ("- - - -"). Initialize the Mirror to perform initial transfer of contents from source volume to destination volume
2	Select the "Update Snapmirror after operation" option for the operation.
3	If any volume whose data is captured in the backup is a SnapMirror source volume, SnapDrive requests information about all SnapMirror destination volumes for the source volume.
4	SnapDrive sends a SnapMirror destination update request to all the related destination volumes.
5	SnapMirror updates the destination volumes to reflect incremental changes on the source volume.