Reverse Restore; Fast Reverse Restore; Options And Interfaces - IBM System storage DS6000 Series Redbook

7.8 Reverse restore

With this option the FlashCopy relationship can be reversed by copying over modified tracks
from the target volume to the source volume (see Figure 7-7). The background copy process
must complete before you can reverse the order of the FlashCopy relationship to its original
source and target relationship. Change recording is a prerequisite for reverse restore.
source volume
will become
target volume
no updates in source
updates took place
in source volume
updates took place
in source volume
no updates in source
Figure 7-7 Reverse restore
The source and target bitmaps (illustrated in Figure 7-4 on page 57) are exchanged and then
handled as described with the Incremental FlashCopy option.

7.9 Fast reverse restore

This option is used with Global Mirror. If you specify this option, you can reverse the
FlashCopy relationship without waiting for the completion of the background copy of the
previous FlashCopy.

7.10 Options and interfaces

Now that we have discussed the options available with FlashCopy, let us see how the
DS6000-provided interfaces and the z/OS-provided interfaces support them; see Figure 7-8
on page 61.
60
IBM System Storage DS6000 Series: Copy Services with IBM System z
target volume
source volume
nothing to be done
as data was already
copied from source
to target and is
no updates in target
identical on both
sides
no updates in target volume
data of previous
target (now source)
updates took place
will be copied to
previous source
updates took place
(now target)
will become
in target volume
in target volume