The direction of a FlashCopy relationship can be reversed, where the volume that was previously defined as the target becomes the source for the volume that was previously defined as the source (and is now the target). The data that has changed is copied to the volume previously defined as the source.
You can reverse a FlashCopy relationship if you want to restore a source volume (Volume A) to a point in time before you performed the FlashCopy operation. In effect, you are reversing the FlashCopy operation so that it appears as though no FlashCopy operation ever happened. Keep in mind that the background copy process of a FlashCopy operation must complete before you can reverse volume A as the source and volume B as the target.
There might be certain circumstances when you might want to reverse
an original FlashCopy relationship. For example, suppose you create
a FlashCopy relationship between source volume A and target volume
B. Data loss occurs on source volume A. To keep applications running,
you can reverse the FlashCopy relationship so that volume B is copied
to volume A.
Note: A fast reverse option that applies to a Global Mirror operation
allows a FlashCopy relationship to be reversed without waiting for
the background copy of a previous FlashCopy relationship to finish.
A Global Mirror operation
is based on existing Global Copy and
FlashCopy operations at the target site.
Figure 1 illustrates
how a reverse restore operation works:
Figure 1. Refreshing
target volume — reverse restore