HP XP P9500 Storage - Manual (Page 48)

For more information about splitting pairs, see “Splitting consistency group pairs with consistency
group pair-split” (page 119) . For more information about troubleshooting consistency group pair-split
and the consistency group pair-split option, see “Troubleshooting the consistency group pair-split”
(page 68) .
1. Define a consistency group for the BC pairs that you are splitting. Complete the following:
a.
Specify the consistency group as a BCM copy group and select a split type: Quick Split
or Steady Split.
b. Register the split time. The split type changes to Quick Split.
For more information about splitting pairs and the split type, see “Splitting pairs, creating and
splitting pairs” (page 117) .
2. Specify the consistency group pair-split option, then create the pairs.
3. Ensure that all BC pairs in the consistency group are in PAIR or COPY(PD)/COPY status.
4. Split the pairs in the consistency group.
The pairs are split simultaneously.
NOTE: You cannot maintain BC S-VOL consistency if you are sharing a BC P-VOL with Cnt Ac-J
S-VOLs and you have included BC pairs in a status other than PAIR or COPY(PD)/COPY in the
consistency group.
Pair resynchronization
You resynchronize a pair that is split or suspended by the system. Resynchronizing updates the
S-VOL so that it is again paired with the P-VOL.
CAUTION: Resynchronizing the pair does not guarantee that P-VOL data is the same as S-VOL
data. Data in the two volumes is the same only if the P-VOL is offline and the pair has been split
(PSUS status).
Related information
•
“Types of resync operations” (page 48)
•
“Prerequisite information for resynchronizing” (page 49)
•
“Resynchronizing pairs” (page 50)
Types of resync operations
You can resynchronize pairs from P-VOL to S-VOL and from S-VOL to P-VOL. The types of resync
operation are as follows:
•
Normal Copy. Forward full resync, from P-VOL to S-VOL.
The P-VOL is accessible to hosts for both read and write operations. ◦
◦ The S-VOL is inaccessible to hosts.
•
Quick Resync. Forward resync from P-VOL to S-VOL but does not data copy. The status changes
to PAIR but does not resynchronize the data to the S-VOL.
◦ Differential data is copied to the S-VOL during update copying.
◦ The P-VOL is accessible to hosts for read and write operations.
◦ Data in the P-VOL and S-VOL may not be the same after a Quick Resync even when there
a host I/O is not present during the operation. Split the pair to ensure that data is the
same.
48 Performing pair operations