HP XP P9500 Storage - Manual (Page 115)

D Pair operations (secondary window)
This appendix provides instructions for performing pair operations using the previous RWC GUI,
which opens in a secondary window.
Pair operations workflow
A typical pair-operations workflow follows:
•
Check pair status. Each operation requires a pair to have a specific status. You also check
pair status to ensure that an operation completed successfully.
•
Create the pair, in which the S-VOL becomes a duplicate of the P-VOL. Once the copy process
completes, you can create the pair and immediately split it so that you can have instant access
to the S-VOL.
•
Split the pair, which separates the primary and secondary volumes and allows use of S-VOL
data by secondary applications.
•
Resynchronize the pair, in which the S-VOL is again updated from the P-VOL.
•
Delete the pair, in which the pair relationship between the pair volumes is ended, though the
data remains.
Check pair status
Every pair operation requires the pair to have a specific status. When you want to perform a pair
operation, check pair status to ensure that you can proceed successfully.
•
For pair status definitions and instructions for finding pair status, see “Monitoring the system
” (page 53) .
•
For the operations allowed for specific pair statuses, see “Status, pair operations permitted ”
(page 55) .
•
When you have L2 pairs, besides checking pair status, you will also check whether an operation
is possible given the status of related L1 and L2 pairs. For information, see
“Status for L1, L2
pairs and operations permitted” (page 55) .
Creating L1 and/or L2 pairs
When you create the initial copy, data in the P-VOL is copied to the S-VOL. During the operation,
the P-VOL can receive updates from the host. When the initial copy is completed, the updated data
in the P-VOL—differential data—is copied to the S-VOL periodically (update copy).
You can create the pair and immediately split it so that you can have instant access to the S-VOL.
For more information about creating and splitting pairs, see
“Splitting pairs, creating and splitting
pairs” (page 117) .
You can create pairs for L1 or L2. Instructions for both procedures are included in this section.
Prerequisite information
•
Make sure that your volumes are set up for pairing. For more information, see “Planning pair
volumes” (page 13) .
•
If the P-VOL is used with another pair, the pair status of the existing pairs must be PAIR.
•
If the P-VOL is not used with another pair, the P-VOL and S-VOL must not be assigned to a
pair (SMPL status).
•
Because pair creation affects performance on the host, observe the following:
Create a pair when I/O load is light. ◦
◦ Limit the number of pairs that you create simultaneously.
Pair operations workflow 115