HP XP Racks - Manual (Page 54)

When a pair is split:
•
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 split operation.
•
Pair status changes to PSUS.
•
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.
•
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.
•
Another option is to enable system write to the S-VOL from a host. The secondary system
records the updated tracks as differential bitmaps. When the pair is resynchronized, the
secondary system sends the differential bitmaps to the primary system, which merges all
differential bitmaps to determine which tracks are out-of-sync.
Prerequisite information
•
Pair status must be COPY or PAIR.
Procedure 11 To split one or more pairs
1. In the Storage Systems tree, click Replications > Remote Replications.
2. In the Remote Replications window, click the Cnt Ac-S Pairs tab, then select the pair to be split.
3. From the Actions menu, click Remote Replications > Split Pairs.
4. In the Split Pairs window, ensure that the pair to be split appears in the Selected Pairs table.
5. For Secondary Volume Write, specify whether the host can write to the S-VOL while the pair
is split.
•
Enable. Accepts host writes to the S-VOL. Note the following:
- If you plan to resynchronize the pair after the S-VOL has been written to while split, you
must select Depend on Primary Volume Fence Level for the Primary Volume Write option,
below. This ensures that P-VOL and S-VOL bitmaps are merged when the pair is
resynchronized.
- If you specify Enable for this option, and also need the P-VOL to continue accepting host
I/O, make sure to select Depend on Primary Volume Fence Level for Primary Volume
Write.
54 Cnt Ac-S pair operations