HP XP P9500 Storage - Manual (Page 58)

10. Copy Pace – Enter the maximum number of tracks to be copied during the initial copy. The
default value is 15.
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Between 1 and 5 is slow, and is used to reduce impact to host I/O.
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Between 5 and 10 is a medium pace.
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Between 11 and 15 is a fast pace. Host I/O performance can be lowered.
11. From the Priority list, specify the scheduling order for the initial copy operation. The default
value is 32, and 1 to 256 can be specified.
Priority applies to those initial copies specified when Apply is clicked. Additional initial copies
specified after the operation begins are not started until the original pairs are completed.
When performing more initial copies than specified for Maximum Initial Copy Activities (during
configuration), see
Priority for initial copy operations and scheduling order (page 24) .
If a time-out error occurs during the Paircreate 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, release the pair with the error, and then retry the Paircreate
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
unit (LU). Default is Auto. For more information, see
“Differential data options” (page 21) .
This option cannot be changed after a pair is created.
13. Click Set.
14. You can review these settings in the Preview pane on the Pair Operation window.
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To modify a setting, right-click the list item and select Modify from the menu.
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To delete an item, right-click and click Delete.
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To delete all items, click Cancel.
15. 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 LU, right-click, and select Error Detail.
Splitting pairs
You can split a pair, which suspends data copying to the S-VOL.
When a pair is split:
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I/O writes from the host continue to the P-VOL, but stop to the S-VOL.
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Any current update copy operation completes to the S-VOL, ensuring data consistency to the
point of the split operation.
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Pair status changes to PSUS.
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The primary system records the updated tracks to the P-VOL that occur after the split as
differential data. This data is copied to the S-VOL when the pair is resynchronized.
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You can set an option to block updates to the P-VOL while the pair is split. This results in the
P-VOL and S-VOL staying synchronized.
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Another option is to enable I/O to the S-VOL from a host. The secondary system records the
updated tracks as differential data. When the pair is resynchronized, the secondary system
sends the differential data to the primary system, which merges all differential data to determine
which tracks are out-of-sync.
58 Pair operations