When your original source volume is available again after a disaster, you can resynchronize data from the destination volume and reestablish the protection relationship.
This procedure replaces the data in the original source volume in an asynchronous relationship so that you can start serving data from the original source volume again and resume the original protection relationship.
Click Protection > Relationships and then click the broken off relationship you want to resynchronize.
Click and then select Resync.
Under Relationships, monitor the resynchronization progress by checking the relationship state. The state changes to "Mirrored" when resynchronization is complete.