To bring up the application on the secondary host
By default, the Enable Fast-Failback Logging option is selected if the data volumes have DCM logs associated with them. You can use this option to perform takeover with fast-failback logging.
The DCM is activated for fast-failback logging and the new incoming writes are marked on the DCM of the New Primary. If the replication status of Secondary RVG was Inactive when the Primary failed, then the Enable Fast-Failback Logging option is unavailable for selection. In this case you can perform Take Over without using fast-failback logging.
Select the Synchronize Automatically option if you want the new Primary and the original Primary to get synchronized automatically, after the original Primary recovers.
If you have not selected this option, the original Primary, after it recovers will be in the Acting as Secondary state. To synchronize this original Primary with the new Primary use the Resynchronize Secondaries option from new Primary RVG's right-click menu. When the resynchronization starts, the original Primary which was in the Acting as Secondary state is converted to a Secondary of the new Primary. The new Primary now starts replaying the DCM to update the Secondary with the writes that were written to the DCM.
After takeover is complete, to add the Secondary hosts of the original Primary as Secondary hosts of the new Primary, delete the existing RVGs of the original Secondary hosts and then add them as a part of the new Primary.
Only after the synchronization is complete can you migrate the Primary role back to the original Primary.
After takeover, the existing Secondary becomes the new Primary.
Now you can start using the application on the new Primary.