HP XP Racks - Manual (Page 56)

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