HP StorageWorks XP24000 Continuous Access Software User and Reference Guide, v01 (T5278-96002, June 2007)

Releasing Conti
nuous Access Pairs
A Continuous Ac
cess pa ir should be released from the MCU only when it is no longer necessary to
maintain a remo
te
copy of the P-VOL. When a Continuous Access pair is released from the MCU, the
MCU
stops all update copy o perations for that pair and changes the pair status of the P-VOL and S-VOL
to
SMPL. After a Continuous Access pair is released, the MCU continues to accept all subsequent write
I/O
operations to the P-VOL and will not keep track of the P-VOL updates.
AContinuous A
ccess pair s hould be released from the RCU only for disaster recovery (see
“Usage Scenarios” on page 127). When a Continuous Access pair is released from the RCU, the RCU
changes the S-VOL pair status to SMPL, but does not change the pair status of the corresponding P -VOL.
When the
MCU per forms the next Continuous Access operation for that pair, the MCU detects that the
S-VOL status has changed and changes the P-VOL status to PSUS-pairsplit-S to RCU. To restart a pair that
was released from the RCU, you must first release the pair from the MCU, and then create the pair from
the MCU usin
g
the appropriate initial copy option (Entire Volume or None) to restart the pair.
To release all Continuous Access Asynchronous pairs in a consistency group, you must release the pairs
from the MCU. The Continuous Access pair status will change to Deleting when the pairsplit-S operation
is
accepted by the MCU and RCU, and then to SMPL after the internal pairsplit-S process is complete. To
release Continuous Access Asynchronous pairs according to their consistency status (for example, for
disaster recovery), you must release the pairs from the RCU.
WARNING: W
hen
you release a Continuous Access pair from the RCU, remember that the S-VOL an d
P-VOL are identical (for example, same volume label), and take appropriate p recautions to prevent a
system problem due to duplicate volumes.
WARNING:
As a general rule, when you want to release a Continuous Access Asynchronous pair from the
MCU, HP st
rongly recommends that you per form the pairsplit-S operation after the update copy o peration
is
compl
eted. If you request the pairsplit-S operation while the update copy process is still in progress, it
may take a long time to complete the pairsplit-S operation. However, when you urgently need to release
a
Continuous Access Asynchronous pair, you can perform the pairsplit-S operation from the RCU. In this
case, you will find the PSUE status a t the MCU after performing the pairsplit-S operation from the RCU.
The Pair
split-S dialog box (see Figure 52 on page 121) allows you to release Continuous Access pairs
and select the pairrelease options. To open the Pairsplit-S dialog box, click the Pair Operation tab,
select a CU grouping, CU, port, or host group from the tree, select the desired pair(s), right-click, and
then
click Pairsplit-S command.
120
Performing Continuous Access Pair Operations