Dell EqualLogic PS6210XS EqualLogic Group Manager Administrator s Guide PS Ser - Page 273

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 offline. b. Perform a final 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 Effective 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 configured 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 specific 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 configuration. 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 configuration. 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. About Data Recovery 273