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Managing MP unit assignment

Enabling and disabling MP unit auto assignment

Use this procedure to enable or disable auto assignment of a specific MP unit.

When auto assignment is enabled, the MP unit can be automatically assigned to resources in the storage system (logical devices, external volumes, and journal volumes). When auto assignment is disabled, the MP unit cannot be automatically assigned to resources in the storage system. For details about how MP units are assigned to resources, contact customer support.

CautionEnabling and disabling MP unit auto assignment can have a significant impact on storage system performance. Contact customer support for assistance before enabling or disabling auto assignment of an MP unit.

Before you begin

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

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Expand Components, and click the controller (DKC) containing the MP unit that you want to change.

  3. On the MP Units tab, select the MP Unit ID of the MP unit that you want to change, and then click Edit MP Units.

    When the Edit MP Units window opens, the current auto assignment setting of the selected MP unit is displayed. For example, if auto assignment is currently enabled, the Edit MP Units window opens with Enable selected.
  4. In the Edit MP Units window, select Enable to enable auto assignment for the selected unit, or select Disable to disable auto assignment for the selected unit.

  5. Click Finish.

  6. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  7. Click Apply.

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

Changing the MP unit assigned to an LDEV

Use this procedure to change the MP unit assigned to an LDEV.

Before you begin

The Storage Administrator (System Resource Management) role is required to perform this task.
Caution
  • 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, you should use 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 you try to change the ID again for the same LDEV.

Procedure

  1. Click Storage Systems, and then expand the Storage Systems tree.

  2. Click Logical Devices.

  3. In the Logical Devices window, select the LDEV ID of the LDEV that has the MP unit you want to change.

  4. Click More Actions, and then select Assign MP Unit.

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

  6. Click Finish.

    The Confirm window appears.
  7. In the Task Name text box, type a unique name for the task or accept the default.

    You can enter up to 32 ASCII characters and symbols, with the exception of: \ / : , ; * ? " < > |. The value "date-window name" is entered by default.
  8. Click Apply.

    If Go to tasks window for status is selected, the Tasks window appears.