HP XP P9000 Continuous Access Synchronous for Mainframe Systems User Guide

The CESTPAIR TSO command does not support the option for scheduling order for the initial
copy operation. When the Cnt Ac-S Z pair is created with CESTPAIR command, initial copy
operation is performed according to the order that CESTPAIR is run.
If a time-out error occurs during the Add Pair operation, the order specified in Priority may
not run correctly. A time-out error may occur because of the CU configuration, or by a data
path error. Review the error, delete the pair with the error, and then retry the Add Pair
operation.
12. From the Difference Management list, select the method for managing differential data. With
Auto, either Cylinder or Track is used by the system, depending on the basic size of the logical
volume image (LVI). Default is Auto. For more information, see “Differential data options”
(page 36).
This option cannot be changed after a pair is created.
13. From the CFW Data list, select whether the CFW data will be copied to the S-VOL.
• Copy to S-VOL: CFW data is copied to the secondary volume.
• Only P-VOL: CFW data is not copied to the secondary volume.
14. From the DFW to S-VOL list, select whether the main system suspends the pair if the remote
system cannot run DFW (DASD fast write) to the S-VOL.
The interaction of DFW required and the P-VOL fence level setting can cause a host application
to fail with a permanent I/O error when attempting to update an P-VOL. Keep track of which
pairs have the DFW required setting, and make sure that DFW to the S-VOL is not blocked.
If a Cnt Ac-S Z pair is established using PPRC commands, the DFW to S-VOL option is set to
the DFW not required setting.
15. From the Time Stamp list, select whether or not the host I/O time stamp is transferred from
P-VOL to S-VOL.
16. Click Set.
17. You can review these settings in the Preview pane on the Pair Operation window.
• To modify a setting, right-click the list item and select Modify from the menu.
• To delete an item, right-click and click Delete.
• To delete all items, click Cancel.
18. When satisfied, click Apply.
If the operation does not start normally, an error code displays in the Error Code column in the
Preview list. To display an error message, select the LDEV, right-click, and select Error Detail.
Suspending pairs
You can suspend a pair, which suspends data copying to the S-VOL.
When a pair is suspended:
• I/O writes from the host continue to the P-VOL, but stop to the s-VOL.
• Any current update copy operation completes to the s-VOL, ensuring data consistency to the
point of the suspend operation.
• Pair status changes to Suspend.
• The main system records the updated tracks to the P-VOL that occur after pair suspension as
differential data. This data is copied to the S-VOL when the pair is resynchronized.
• You can set an option to block updates to the P-VOL while the pair is suspended. This results
in the P-VOL and S-VOL staying synchronized.
• Another option is to enable I/O to the S-VOL from a host. The remote system records the
updated tracks as differential data. When the pair is resynchronized, the remote system sends
68 Pair operations