What happens when you add volume replication option to NAS Logical Volume that is already used by local backup?

Article ID: 1443

Last updated: 13 Oct, 2011

Generally adding the “volume replication” option in DSS WebGUI -> CONFIGURATION -> volume manager -> vol. groups -> vgxx -> volume manager -> action: modify lvxxxx -> “Use volume replication”
causes a change of the LV UUID (logical volume identification info).
If you use local backup functionality each time a backup job starts it runs a snapshot. The snapshot is assigned to a NAS logical volume and it identifies to which logical volume it is assigned using LV UUID.

When a volume replication is enabled for the NAS logical volumes that are being backup-ed, its LV UUID is changed. As a result the snapshot is using the old LV UUID that no longer exists and it can’t find the logical volume to which it is assigned. It is frozen and can neither be stopped nor started. This may lead to several problems with backup tasks.

Please also remember that each time you add or remove the volume replication functionality to an existing logical volume, you need to unassign the snapshot from the logical volume and assign the snapshot back to the logical volume after the volume replication is added/removed.
You also need to delete the backup tasks that are using this snapshot and recreate them.

In the DSS V6 b5626 this it’s already forbidden to add “volume replication” to a NAS logical volume without deleting the back tasks before and unassigning the snapshot from that logical volume. This should prevent the occurrence of the mentioned failures.