Deleting a UR pair

When you delete a pair, the UR relationship between the P-VOL and S-VOL is released. Only the relationship is affected, the data volumes and their data remain.

Before you begin

• You must have the Storage Administrator (Remote Backup Management) role.

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

• When S-VOLs are physically attached to the same host as P-VOLs, take the S-VOLs offline before releasing the pair. Doing this avoids confusion and possible error when the host is restarted.

• Pairs must be in Suspend status when their journal is in a CCI consistency group consisting of multiple primary and secondary storage systems. If all pairs in the journal are not in Suspend status, you can delete the desired pairs individually, or select Mirror in the Range field, which deletes all pairs in the pair’s mirror.

The following additional information might be useful to you before beginning the procedure:

• When a pair deletion is initiated, differential data is transferred from the S-VOL, the pair relationship is ended, and the volumes’ status becomes unpaired.

• Pairs should be in PAIR status to ensure data consistency between volumes. However, a pair can be deleted in any status except Suspending or Deleting.

• If you delete a UR pair between the intermediate and secondary sites in a 3DC cascade configuration in which three UR sites are combined, change the status of the mirror between the primary and the intermediate sites to Stopped, or change the status of the pair you want to delete to Suspending.

• If the operation fails, the P-VOL nevertheless becomes unpaired, but transfer of differential data to the S-VOL is terminated.

• If you plan to delete all pairs in the journal and then create another pair, be sure to wait at least one minute after deleting the pairs before creating the new pair.

• Perform pair deletion when write I/O load is low to reduce impact on performance. Operations on pairs with different status in the same mirror may result in suspension during periods of heavy write I/O.

• If you delete pairs in PAIR status and other than PAIR status in the same mirror, an unexpected suspension could 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.

• In a delta resync configuration with TC, if you release the TC pair, the UR delta resync pair is released as well. If you release the UR pair, the UR delta resync S-VOL is released.

• In a delta resync configuration with GAD, release the pairs in the order of UR pair first, UR delta resync pair second, and then finally the GAD pair.

Procedure

1. Open the Remote Replication window:

In Command Suite:

1. On the Resources tab, expand the Storage Systems tree.

2. Right-click the target storage system, and click Remote Replication.

In Device Manager - Storage Navigator:

1. In the Explorer pane, expand the Storage Systems tree.

2. Expand the target storage system tree, expand Replication, and click Remote Replication.

2. In the UR Pairs tab, select the pairs to be deleted and click More Actions > Delete Pairs.

3. In the Delete Pairs dialog box, review the pairs in the Selected Pairs table. To remove a pair from the table, select the pair and click Cancel.

4. For Delete Mode, Normal is used for UR.

 Note the following:

• Forced deletion in the primary storage system results in data that was not yet sent to the secondary storage system being deleted.

• Forced deletion in the secondary storage system results in data that was not yet restored being deleted.

• If pair status has not changed to SMPL five minutes after you forcibly delete the pair, delete it again.

• Make sure not to re-create the pair in the first five minutes after forcibly deleting it using the same journals (mirrors), even if pair status is SMPL and journal status is Initial: in this case pair creation could fail and the pair might suspend.

• A time-out error can occur at the time of a forced deletion if I/O is sent to another pair in the same journal and the pair’s status is PAIR or COPY.

5. Click Finish.

6. In the Confirm window, review the settings, enter a task name, and then click Apply.