When disaster strikes on a production data center, the takeover operation is invoked to start the resiliency groups on the recovery data center.

Since the production data center is not working, the data replication between the two sites does not happen. After the production site is back up and running, you need to prepare the production site for the next failover or for a migration operation. This preparation includes cleaning up any residue and resuming the replication from the recovery to the production site.

Use the Resync operation on the Resiliency Platform console to automate these steps for the required resiliency groups. This operation cleans up the residue which includes stopping applications and virtual machines, unregistering virtual machines, unmounting file systems, datastores, etc. If the recovery data center is Amazon Web Services, then the virtual machines are not unregistered.

In Microsoft Failover Cluster environments, the Resync operation may fail in the first step to cleanup the virtual machine residue. You can manually cleanup the virtual machine residue and proceed.

See Manually cleaning up virtual machines.

If the recovery data center is in cloud, and if while configuring the resiliency group for remote recovery, the Enable reverse replication option was selected, then do not run the Resync operation till the replication is complete and the state is IN Sync.

If the Resync operation fails, check Recent Activities to know the reason and fix it. You can then launch the Retry operation. The Retry operation restarts the migrate workflow, it skips the steps that were successfully completed and retries those that had failed.

Do not restart the workflow service while any workflow is in running state, otherwise the Retry operation may not work as expected.