Getting to know Dell PowerFlex v3.6.x

Recovering from disaster

There are several ways to recover from a disaster. Doing so allows the target volumes to be accessible to the hosts and to take over as the replication source.

The following are options for recovering from a disaster:

• Failover—Fail over the RCG. During failover, the application I/Os are stopped at the source and the access mode of the source volumes is changed to inaccessible. The target volumes are brought to the newest consistent image available on the destination and their access mode is changed to read-write. Recovery from failover state can be achieved by either restoring the replication or reversing it.
• Test failover—Test failover of the RCG. This allows you to demonstrate failover mode without interrupting data synchronization.
• Switchover—Switch over the RCG. Switchover is a planned failover. The application I/Os are stopped at the source and the data is synchronized so that the target volume is consistent with the source volume. The access mode of the original source volumes is changed to unavailable or read-only. The access mode of the original target volumes is changed so that the hosts can read and write to the volumes.

Target volumes can be mapped only once failover or switchover has been performed. Once the RCG is in failover or switchover mode, you can decide how to continue with replication:

• Restore replication—This maintains the replication direction from the original source and overwrites all data at the target.
• Reverse replication—This changes the direction so that the original target becomes the source. All data at the original source is overwritten by the data at the target.