Administrator Guide

a. Demote the original volume to a failback replica set on the primary group.
b. Replicate the recovery volume to the primary group. If you kept the failback snapshot for the original volume, only the
changes made to the recovery volume are replicated.
3. When you are ready to fail back to the primary group, use the Failback to Partner operation to:
a. Set the recovery volume oine.
b. Perform a nal replication to synchronize the volume data across both groups.
c. Demote the recovery volume to an inbound replica set.
d. Promote the failback replica set to a volume and snapshots. The volume represents the data that was in the most recent
complete replica. The snapshots correspond to any additional replicas.
Recover Data from a Replica
If you replicate a volume to a partner, you can recover volume data from the partner. In addition, you might be able to fail over to the
partner and later fail back to the original group.
If a volume is destroyed, you can fail over to the recovery group and recover data from a replica. Users can then resume access to
the recovery volume. When the original volume becomes available, you can fail back to the original group.
About Data Recovery from a Replica
Eective data recovery requires a well-planned disaster-protection strategy and the regular creation of replicas and backups. To
protect volume data from unrecoverable failure, you can replicate a volume to a group congured as a replication partner.
If the volume becomes unavailable, either temporarily or permanently, you can recover the data from the partner. The method of
recovering data depends on the state of the groups and your specic data-recovery requirements.
When volume failure occurs, or if the primary group is unavailable because of maintenance, it is important to resume data availability
as soon as possible to prevent or limit application downtime.
For example, you can clone a replica to create a new volume on the secondary group. The new volume contains the same data that
existed at the time you created the replica; initiators can connect to it in the usual way. Cloning a replica has no impact on the original
volume and the replication conguration. If the original volume is still available, replication can continue as usual.
In most situations where you need to recover data, the primary group is not available because of maintenance or a failure. In this
case, you can temporarily or permanently fail over the volume to the secondary group and make the volume data available to
initiators. If the original volume on the primary group becomes available again, you can fail back the volume to the primary group,
returning to the original replication conguration.
You implement failover and failback by using the following operations:
• Promote
Enables you to convert a replica set into a volume and snapshots. The volume contains the data represented by the most recent,
complete replica. The snapshots correspond to the remaining replicas.
For example, you can promote an inbound replica set to a recovery volume as part of a failover operation.
• Demote Enables you to convert a volume into a replica set.For example, you can demote a volume to a failback replica set as part
of a failback operation.
About Permanently Promoting a Replica Set to a Volume
You can permanently promote a replica set in a single operation, resulting in a new standard volume, template volume, or thin clone
volume. You might need to perform this task if the original volume is destroyed. Permanently promoting an inbound replica set does
not require any additional space on the secondary group, because it reduces delegated space by the size of the volume’s replica
reserve.
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About Data Recovery