Recovering Data on the Secondary Group
There are several methods you can use to recover volume data stored in replicas on the secondary group. These methods can be used to:
- Provide access to a volume from the secondary group and optionally fail back to the primary group.
- Back up volume data from the secondary group.
- Test your replication configuration.
- Switch roles in a replication configuration (that is, the original secondary group becomes the new primary group, and the original primary group becomes the new secondary group).
The methods of recovering data differ in results and in the amount of space required in the secondary group. For example, you can:
- Clone a replica. This creates a new volume on the secondary group with a new name, but the same size and contents as the original volume at the time the replica was created. The replica still exists after the cloning operation, and volume replication from the primary group is not affected. Cloning a replica requires additional space in the secondary group (equal to the volume reserve at the time the replica was created).
See Cloning an Inbound Replica for more information.
- Promote a replica set. This transforms the replica set into a volume and a set of snapshots that correspond to each complete replica. The volume will contain the data represented by the most recent complete replica and can be accessed by initiators as usual. Delegated space is reduced by the size of the replica reserve; no additional space is needed on the secondary group.
There are two options for promoting a replica set:
Temporary promotion. You can temporarily promote an inbound replica set to a recovery volume and snapshots, while retaining the ability to later demote the recovery volume and snapshots to the original replica set.
Use this option when the primary group is unavailable because of failure or maintenance or if you want to temporarily host the volume from the secondary group for backup purposes.
Any changes that are made to the recovery volume are tracked in the secondary group, so you can later fail back those changes if the original volume becomes available. If you chose to keep the failback snapshot when configuring replication on the volume, you may be able to fail back by replicating only the volume changes, instead of the entire volume contents.
Permanent promotion. You can permanently promote a replica set to a volume that is not a recovery volume. In addition, if you promoted an inbound replica set to a recovery volume, you can make this promotion permanent. In both cases, a permanent promotion disables the ability to later demote the volume to the original inbound replica set.
Use this option if the original volume has been destroyed and you are sure you cannot recover the volume.