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12 Using Dell PS Series Asynchronous Replication | TR1052
If you decide to enable failback support, you can specify it at the time you initially configure replication on
the volume, or at any time thereafter.
Note: You must create a replica to establish the failback snapshot before you attempt to failback.
Because the failback snapshot uses space from the volume’s local replication reserve, you may want to
increase that value to ensure replication continues to succeed.
The general overview of the failback process is as follows.
1. On the primary group, the original volume becomes unavailable, or the primary group becomes
unavailable.
2. On the secondary group, promote the replica set (section 5.1.4). The promoted volume is called a
recovery volume.
3. Connect host initiators to the recovery volume (section 5.1.5). Hosts can continue to access the
data via the recovery volume.
4. The primary group becomes available again.
5. Replicate the recovery volume back to the original group (section 5.1.6). Two things occur
automatically:
a. On the primary group, the original volume is demoted to a failback replica set.
b. On the secondary group, the recovery volume is replicated to the primary group.
If the original volume has a failback snapshot, only the differences will be replicated. If not, the
entire contents of the recovery volume are replicated.
6. If the failback operation will not happen immediately, set up a replication schedule (section 2.6) on
the recovery volume to keep the two groups synchronized.
7. As soon as the replication operation completes, failback to primary (section 5.1.7).