Changing the MP unit assigned to an LDEV

• Changes to the MP unit ID of an LDEV should be made during off-peak hours when the I/O load is as low as possible. Before and after changes are made, it is recommended that the cache write-pending rate (%) for all CLPRs is lower than 50%. Do not change the MP unit ID when the I/O load is high: for example, during initial copy of ShadowImage, TrueCopy, global-active device, or Universal Replicator).

• When you change the MP unit ID of an LDEV, use the Performance Monitor before and after the change to check the load status of devices. Do not change several LDEV MP unit IDs during a short period of time. As a guideline, you can change 10% or less of the total number or the full workload of LDEV MP unit IDs assigned to the same MP unit ID at the same time.

• After you change the MP unit for an LDEV, wait more than 30 minutes before changing the ID again for the same LDEV.

The Storage Administrator (System Resource Management) role is required to perform this task.

1. Perform one of the following to display the Logical Devices window.

For Command Suite:

• On the Resource tab, expand the Storage Systems tree. Right-click Volumes of the target storage system, then select System GUI. On the LDEVs tab, select Assign MP Unit.

For Storage Navigator:

• In the Storage Systems tree on the left pane of the main window, select Logical Devices.

LDEVs appear in the LDEVs tab.

2. Select the LDEV for which you want to change the MP unit.

3. Perform one of the following to display the Assign MP Unit window.

• Click More Actions, then select Assign MP Unit.

• Click Actions > Logical Device > Assign MP Unit to open the window.

4. In the Assign MP Unit window, specify the MP unit in MP Unit.

5. Click Finish.

6. In the Confirm window, confirm the settings, in Task Name type a unique name for this task or accept the default, then click Apply.

If Go to tasks window for status is checked, the Tasks window opens.