Prerequisites for failing back from the Business Continuance site

Before you start a planned failback operation from the Business Continuance site, execute the Business Continuance plan cleanup task, start reverse resynchronization from the destination to the source storage system, and flush the local DNS cache.

If you have a clustered configuration and already have a production site where you performed Business Continuance, execute the Business Continuance plan cleanup task to remove the remaining Exchange resources and to disconnect the old LUNs.
Perform this cleanup before you resynchronize the mirrors in the reverse direction.
From the Replication Management Console, initiate reverse resynchronization from the destination storage system to the source storage system.
Verify that the SnapMirror relationship is in a state from which a transfer can take place.
Flush out the local DNS cache and delete the stale entries after the failover process.
Note: After failover\failback from the Business Continuance site, you might need to update the new IP in reverse lookup zone of DNS.

The local DNS cache in the Business Continuance site (all of the nodes of the Business Continuance cluster for a clustered configuration) are flushed automatically as a part of the recovery operation. If the IP address is different in the disaster recovery site, the automatic flush enables the connection to SnapManager from the Business Continuance server after a recovery operation without a manual removal of the local DNS cache.
Make sure that each SnapMirror alias is unique in its system and that there is not any other invalid, stale, or old destination volume relationship for the same destination volume.
To remove any prior history, run setup.com /clearlocalcms /cmsname:<> on the destination cluster.
Note: The cleanup task also performs clearlocalcms automatically.
Ensure that any LUN clone split operation that is in progress is complete.
To check that any LUN clone split operations are complete, use the storage system’s lun clone split status command, or view the Operation Status column in the SnapDrive Microsoft Management Console (MMC).

For detailed information about this command, see the Data ONTAP Block Access Management Guide for iSCSI and FC.

The LUN clone split functionality, introduced in Data ONTAP 7.1, supports significantly faster online Snapshot copy restore times when using SnapManager or SnapDrive to restore database. By default, this functionality is enabled.

Attention: If you attempt a failback procedure immediately after a failover, that uses a LUN clone split (such as a test of a failover and failback), the LUN clone split operation might interfere with SnapMirror during resynchronization with the data back to the production site.