Resynchronization of FlashCopy volume pairs

FlashCopy volumes resynchronization (resync) provides the ability to update an initial point-in-time copy of a source volume.

You can resync your FlashCopy volumes without having to recopy your entire volume. This process is only possible with a persistent relationship, whereby the storage unit continually tracks updates to the source and target volumes. With persistent relationships, the relationship between the source and target volumes is maintained after the background copy has completed.

This function reduces the background copy completion time because only a subset of data is copied when either the source or target volume has changed. The target volume becomes current with the newly established point-in-time source copy.

To enable this function of FlashCopy, the storage unit uses a feature called change recording to monitor write operations and record changes that were made to volumes participating in FlashCopy relationships since the initial (or last) incremental FlashCopy was performed. After the initial copy of the source volume to the target volume, the FlashCopy relationship between the volumes is not automatically deleted. Rather, it remains to allow the volumes to be resynchronized. The next time that you want to update the information on your target volume, you can resync your target volume again.