The Fast Reverse Restore function, available for both Compatible FlashCopy® V2 and CFCSE, enables you to simplify data recovery. This function reverses the original S-VOL and T-VOL relationship established by Compatible FlashCopy® V2. This reversal re-establishes the relationship with the data flowing in the opposite direction. The Fast Reverse Restore function is available for CFCSE only if the Incremental FlashCopy® function is not in use.
You cannot perform the Fast Reverse Restore function in the following cases:
- The relationships to be reversed include a relationship established with multiple volumes.
- The T-VOL capacity exceeds the S-VOL capacity in the relationship to be reversed.
- The original relationship was re-established using the Fast Reverse Restore function.
- The original relationship was established using CFCSE, and the Incremental FlashCopy® function is in use. A relationship established using Incremental FlashCopy® cannot be created using CFCSE, so this describes the existence of multiple relationships.
You can perform the Fast Reverse Restore function on a relationship established in NOCOPY mode or during the copy process. If you perform the Fast Reverse Restore function during the copy process, the copy process will terminate.
After you re-establish a relationship by using the Fast Reverse Restore function, the contents of the new S-VOL are not ensured, as they will be changed by any host write operations.
You can determine whether you can perform the Fast Reverse Restore function from the execution result of the FLASHCOPY QUERY RELATIONS command of ICKDSF. For details, see Displaying information about Compatible FlashCopy V2 relationships: FLASHCPY QUERY RELATIONS.
When you perform the Fast Reverse Restore function using the Incremental FlashCopy® function, only the updated data is copied from the newly specified source volume to the target volume.
You can use the Fast Reverse Restore function regardless of the incremental type (Type1 or Type2). However, you cannot change the incremental type of existing relationships using the function. When using the function, if you specify the parameter to change the incremental type of the existing relationship, the command is rejected.
When you perform the Fast Reverse Restore function, only the updated data is copied from the newly specified S-VOL (former T-VOL) to the T-VOL (former S-VOL) as with ordinary relationship re-establishment. The updated Data 2A in the target volume is then lost (as shown in the following figure).
The Incremental FlashCopy® workflow of Fast Reverse Restore is shown in the following figure.