HP StorageWorks XP12000 User Manual page 109

• Pending Update:
Drain: The MCU changes the Continuous Access XP Async pair status from Suspending to PSUS
only after the RCU accepts the pairsplit operation and completes the following steps:
1.
Finishes settling all pending recordsets for the pair.
2.
Completes negotiation with all MCUs (report ready-for-suspension to all MCUs and
receive acknowledgements) without further recordsets generated.
If the RCU cannot complete these actions within the copy pending timeout setting, the RCU
discontinues the original pairsplit-r request and forcibly suspends affected Continuous Access XP
Async pairs. Thus, you can use the copy pending timeout parameter to limit the amount of time
it takes to complete the split-drain operation.
Purge: The MCU changes Continuous Access XP Async pair status from Suspending to PSUS as
soon as the RCU accepts the pairsplit operation. The MCU and RCU discard pending recordsets
and mark cylinders containing discarded recordsets as modified in P-VOL and S-VOL bitmaps,
respectively. When the pair is resumed (pairresync), the P-VOL and S-VOL bitmaps are merged at
the MCU, and all cylinders marked as modified are copied to the S-VOL.
If the MCU does not receive acknowledgement of the pairsplit-r operation from the RCU within
the copy pending timeout setting, the MCU forcibly suspends all affected Continuous Access
XP Async pairs.
NOTE:
If you select a pair from the volume list and change the settings, and then use a drop-down list to set a
parameter to blanks, the parameter takes the default value for each pair. If you select settings from the
Preset list before applying the changed settings, and then use a drop-down list to set a parameter to
blanks in the Pairsplit-r pane, the parameter value in the Preset list does not change.
1.
Connect to the MCU (or RCU) of the volume pairs to be split. You do not need to vary the P-VOLs
offline. To use the S-VOL write enable option, connect to the MCU, and select the P-VOL of the pair.
2.
From the CU Number/Port Number tree on the Continuous Access XP main pane, click the number
of the correct CU image.
3. From the Volume list on the Continuous Access XP main pane, click the Continuous Access XP
volume pairs to be split. Select either Continuous Access XP Synchronous or Continuous Access XP
Asynchronous pairs, but not both. Pair status must be PAIR.
4. Right-click, and click Pairsplit-r. The Pairsplit-r pane appears.
5. Click the options for the pairs, and click Set to close the Pairsplit-r pane and set parameters. The
list changes to the Pair Settings Parameter list (Pairsplit-r). You can modify options as needed (see
Modifying parameters and deleting
suspend kind (S-VOL or P-VOL failure) and fence-level pair options determine whether the P-VOL
accepts write I/O operations after the pair is split.
CAUTION:
If you need to split a pair and the P-VOL is required for system operation, do not use the
P-VOL Failure suspend kind option. Use the S-VOL suspend kind option so the P-VOL
continues accepting I/Os.
6. To execute the pairsplit requests quickly, select the Use Time-Saving Mode check box above the
Pair Settings Parameter list (Pairsplit-r).
7.
Click Apply on the Continuous Access XP main pane to split specified pairs. For Continuous Access
XP Synchronous pairs, the MCU completes all P-VOL write operations in progress and associated
update copy operations at the S-VOL before splitting the pair, so the pair is synchronized at the
time of pairsplit.
LUs). Ensure that pairsplit options for each pair are correct. The
Continuous Access XP user guide
109