HP StorageWorks P9000 - Disk Arrays User Manual page 32

In a reverse Quick Resync (called Quick Restore), the S-VOL and T-VOL are swapped. No
actual data is copied, and the pair is placed in Duplex status.
The S-VOL and T-VOL are inaccessible during this operation. As soon as the Reverse
◦
Copy operation is complete, the S-VOL becomes accessible.
◦ When differential data between S-VOL and T-VOL is small, the Reverse Copy operation
may be completed faster than the Quick Restore operation.
Performing LDEV maintenance work during the Quick Restore process increases time required
to completion.
Prerequisite information
With the Reverse Copy or Quick Restore operation, the pair must be in Split status.
The pairresync normally takes less time when the pair is in Split status than for Suspend status.
This is because the amount of differential data accumulated for a split pair is usually far less
than the total amount of the S-VOL, which must be copied in full if the pair is suspended by
the system.
If you use the DKAs supporting encryption, you can create a Business Copy Z pair by using
an encrypted volume and a non-encrypted volume. For example, you can create the pair
specifying an encrypted volume as the S-VOL and a non-encrypted volume as the T-VOL. In
this case, data in the encrypted S-VOL will be copied as non-encrypted data in the
non-encrypted T-VOL.
If a pair consists of encrypted volumes and a non-encrypted volume, and the Quick Restore
is executed, the S-VOL and T-VOL encryption statuses are reversed.
With a Quick Restore, Remote Web Console may display outdated information. Click
File/Refresh to insure the most up-to-date information.
With a Quick Restore, to keep the S-VOL and T-VOL unsynchronized, enable the Swap&Freeze
option before performing the Quick Restore. Update copy operations are then suppressed
when the Quick Restore is completed and the pair is in Duplex status.
If the reverse or quick restore pairresync operation is performed on one Business Copy Z pair
in a 1 to n Business Copy Z configuration (n>1), the S-VOL and the other T-VOL are no longer
synchronized.
With the Reverse Copy or Quick Restore operation, the following restrictions apply:
Neither Reverse Resync option can be performed on pairs in the Split status.
◦
Pairs sharing the same S-VOL must be in Split or Suspend status.
◦
◦ If the pair shares a volume with Continuous Access Synchronous Z or Continuous Access
Journal Z, and the Continuous Access Synchronous Z or Continuous Access Journal Z
pair is not suspended, neither backward resync operation can be performed.
◦ Quick Restore cannot be performed when Business Copy Z and shared Continuous Access
Synchronous Z or Continuous Access Journal Z volumes include an external volume(s).
You cannot create a Continuous Access Synchronous Z or Continuous Access Journal Z
◦
pair with a volume shared by Business Copy Z during either backward resync operation.
When the Reverse Copy or Quick Restore operation is in progress, you cannot create,
◦
split, or resync any pair sharing the same S-VOL. You can delete or suspend the pairs,
however.
◦ The Quick Restore operation cannot be performed on a Cross OS File Exchange pair.
A PPRC command enables you to resynchronize all BC Z pairs in the same consistency group.
Pairresync operation on all the pairs in the same consistency group works in Normal Resync.
Therefore, you cannot specify Quick Resync, Reverse Copy, or Quick Restore. If you want to
32 Performing pair operations