Splitting a Universal Replicator pair

When you split a pair, write-data is no longer sent to S-VOL and the pair is no longer synchronized. Splitting a pair or mirror gives you a point-in-time copy of the P-VOL.

Prerequisites

• Pair status must be COPY or PAIR.

• This operation can be performed from the primary or secondary system.

• To split multiple pairs at the same time, the pairs must belong to the same mirror. This ensures sequence consistency among S-VOLs in the mirror.

Review the following information before beginning the procedure:

• Splitting the pair when I/O load is low reduces impact on performance. Operations on multiple pairs in the same consistency group with different statuses might result in suspension during periods of heavy write I/O.

• If you split pairs in PAIR status and other than PAIR status in the same mirror, an unexpected suspension might occur during the operation under heavy I/O load conditions. You can estimate whether the I/O load is heavy or not from frequency of host I/Os. This operation should be performed under light I/O load conditions.

• During normal operations, the secondary system rejects write operations to an S-VOL. However, you can enable write operations to the S-VOL while the pair is split by enabling the S-VOL Write option. When this option is enabled and the split pair is resynchronized, the secondary system sends the S-VOL track bitmap to the primary system to ensure proper resynchronization of the pair to the data on the P-VOL. This S-VOL Write option is described in the pair-split procedure.

Procedure

1. Open the Remote Replication window.

In Command Suite: On the Resources tab, expand the Storage Systems tree, right-click the target storage system, and click Remote Replication.

In Device Manager - Storage Navigator: In the Storage Systems tree, click Replication > Remote Replication.

2. Select the UR Pairs tab, and then select the pairs to be split.

3. From the Actions menu, click Remote Replication > Split Pairs.

4. In the Split Pairs window, review the pairs to be split in the Selected Pairs table. To remove a pair from the table, select the pair and click Cancel.

5. For Secondary Volume Write, specify whether data can be written to the S-VOL while the pair is split. This option is available only when you perform the split operation from the primary system.

• Enable: The host can write data to the S-VOL while the pair is split.

• Disable: The host cannot write data to the S-VOL while the pair is split.

6. Click Finish.

7. In the Confirm window, review the settings and enter a task name in the Task Name box.

8. Click Apply to save your settings to the system.