HP XP Continuous Access Software - Manual (Page 87)

Continuous Access XP user guide for the XP1024/XP128 87
• 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:
(a) Finishes settling all pending recordsets for the pair.
(b) 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.
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 LUs ” on page 79). Ensure that pairsplit options for each pair are
correct. The 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.
8. From the Continuous Access XP main pane, verify that Continuous Access XP pairs are displayed
correctly (PSUS status) in the Volume list. Use the Pairresync command (see ” Resuming Continuous
Access XP volume pairs (Pairresync) ” on page 88) to resync split Continuous Access XP volume pairs.
CAUTION: If a timeout error occurs when the Use Time-Saving Mode option is selected, access the
Continuous Access XP main pane, and confirm the volumes on which the pairsplit-r operation could not be
performed. Deselect the Use Time-Saving Mode option for failed volumes, and retry the pairsplit-r
operation.