HP XP Racks - Manual (Page 37)

track of updates while the pair is split. Choose this setting if the P-VOL is required for
system operation and you need to keep the P-VOL online while the pair is split.
6. Click Set. The settings are shown in the Preview area.
7. In the Preview list, check the settings. To change a setting, right-click and select Modify. When
satisfied, click Apply. The primary storage system will complete all write operations in progress
before splitting the pair, so that the pair is synchronized at the time of the split.
8. Verify that the operation is completed successfully by checking the Status column. The status
should be PSUS.
Resynchronizing pairs
When you resynchronize a split pair, the volume that was not being updated—usually the S-VOL—is
synchronized with the volume that was being updated by the host—usually the P-VOL.
Pair status during resynchronization changes to COPY. It changes again to PAIR when the operation
is complete.
The method for performing this operation differs according to whether the P-VOL or the S-VOL is
accepting write I/O from the host. Check the VOL Access column in the Pair Operation window
to see which volume is online.
•
Pairs must be in PSUS or PSUE when the P-VOL is receiving I/O. If status is PSUE, clear the
error before resynchronizing. The operation can be performed using the RWC procedure
below.
•
When the S-VOL is receiving host I/O, pair status must be SSWS. The operation is performed
by running the RAID Manager pairresync-swaps command.
NOTE: If you want to resynchronize the pair that has been released from the S-VOL side, do not
use this procedure. Instead, complete the following:
1. Release the pair from the P-VOL side by running the pairsplit-S RAID Manager command.
2. Create the pair from the P-VOL side using the Paircreate(ESAM) dialog box, making sure to
set the appropriate initial copy option (Entire Volume or None).
1. Access the MCU in RWC, then click Actions > Remote Copy > Continuous Access Synchronous
> Pair Operation.
2. Make sure that you are in the modify mode.
3. In the Pair Operation window tree, select the CU group, CU, port, or host group where the
P-VOL is located.
4. In the volume list, right-click the P-VOL in the pair to be resynchronized and click Pairresync.
In the Pairresync dialog box, P-VOL Fence Level is automatically set to Never. The volume
receiving updates from the host will never be fenced, or blocked, from receiving host
read/write.
5. In the Pairresync dialog box, from the Copy Pace drop-down menu, select the desired number
of tracks to be copied at one time (1-15) during the copy operation. The default setting is 15.
If you specify a large number, such as 15, copying is faster, but I/O performance of the
storage system may decrease. If you specify a small number, such as 3, copying is slower,
but the impact on I/O performance is lessened.
6. From the Priority drop-down menu, select the scheduling order for the copy operations. This
applies when multiple pairs are being resynchronized. You can enter between 1-256. The
highest priority is 1, the lowest priority is 256. The default is 32.
7. Click Set.
8. In the Preview list, check the settings. To change a setting, right-click and select Modify. When
satisfied, click Apply.
Update the pair status by clicking File/Refresh, then confirm that the operation is completed with
a status of PAIR.
Resynchronizing pairs 37