HP XP7 Business Copy for Mainframe Systems User Guide (TK913-96001)

Related topics
• “Forward resynchronization” (page 56).
• “Reverse resynchronization” (page 56).
Forward resynchronization
You can use one of the following methods to forward resynchronize pairs, including the requirements
and restrictions:
• Normal Copy (Primary > Secondary). A full forward resynchronization from the P-VOL to the
S-VOL. During a Normal Copy, only the P-VOL is accessible to hosts for read/write operations.
• Quick Resync (Primary > Secondary). A forward resynchronization from the P-VOL to the S-VOL
where data is not copied or resynchronized. The volumes are paired (“DUPLEX” status). The
update copy operation copies the differential data to the S-VOL.
During a Quick Resync, the P-VOL is accessible to hosts for read/write operations. The S-VOL
is inaccessible to all hosts. Quick Resync, even when a host I/O does not exist, does not
ensure data consistency.
For more information about ensuring data consistency, see “Workflow for ensuring data
consistency” (page 49).
Related topics
• “Splitting BC Z pairs” (page 48).
Reverse resynchronization
You can use one of the following methods to restore pairs, including the requirements and
restrictions:
• Reverse Copy (Secondary > Primary). A full restoration from the S-VOL to the P-VOL. The
differential data is updated to the P-VOL.
During a Reverse Copy you can delete or suspend the pairs, but you cannot create, split, or
resynchronize pairs that share the same P-VOL. The P-VOL is inaccessible to hosts.
If you are sharing a Cnt Ac-S Z or Cnt Ac-J Z volume with an BC Z volume, you cannot create
a Cnt Ac-S Z or Cnt Ac-J Z pair with the shared volume.
You cannot use Reverse Copy the following pairs:
◦ (If you are sharing the P-VOL with an FC Z/FCSE volume) The BC Z pair.
◦ (If you are sharing a volume with an Compatible XRC or Concurrent Copy source volume
(original data)) The BC Z S-VOL.
For more information about sharing volumes with Compatible XRC, see “Sharing volumes
with Compatible XRC” (page 26).
56 Managing Business Copy Z pairs