Assigning mirrors to remote command devices for delta resync operations

You assign the mirror IDs used by the configuration’s journals to the remote command devices. This enables UR control information regarding the delta resync to be transferred and then read at the secondary sites. This is necessary for the delta resync operation.

In RAID Manager, use the raidcom modify journal command.

Before you begin

  • Required role: Storage Administrator (Remote Copy)
  • To assign a mirror to a remote command device, the mirror’s status must be one of the following:

    Initial, Active, Halt, Stopped, Hold, Holding, or Holding(Failure)

    To use a mirror in Initial status, it must have mirror ID 0.

  • Perform this operation for each journal.
  • In a journal, you can assign multiple mirrors to two remote command devices in one operation.
  • A maximum of 16 mirrors can be shared with a remote command device. When a remote command device is shared, you can use it to do the following:
    • Assign it to other mirrors
    • Use it with RAID Manager

    When performing these functions with a remote command device, the number of registered journals and instances used by RAID Manager are subtracted from the number of mirrors that can be shared.

  • A maximum of 16 remote command devices can be used for the delta resync operation per storage system.
NoteA remote command device allocated to a mirror is removed when all pairs in the 3DC delta resync configuration are deleted.

Procedure

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

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

  3. Select the Mirrors tab, and then select the mirror to which you will assign the remote command device.

  4. From the Actions menu, click Remote Replication Assign Remote Command Devices.

  5. In the Available Mirrors table, select a mirror.

    • On primary site:

      - Assign mirror ID 0 to the remote command device that is mapped to the TC secondary site.

      - Assign the mirror ID used for the UR 3DC multi-target pair to the remote command device that is mapped to the secondary site.

    • On the TC secondary site:

      - Assign mirror ID 0 to the remote command device that is mapped to the primary site.

      - Assign the mirror ID used for the UR delta resync pair to the remote command device that is mapped to the UR secondary site.

    • On the UR secondary site:

      - Assign the mirror ID used for the UR 3DC multi-target configuration to the remote command device that is mapped to the primary site.

      - Assign the mirror ID used for the UR delta resync pair to the remote command device that is mapped to the TC secondary site.

    When selecting mirror IDs and remote command devices, observe the following:
    • Though two mirrors can be assigned to each remote command device, it is not required. Mirror 2 is optional.
    • The same mirror ID cannot be specified from both Mirror ID lists.

  6. Select the remote command device to be assigned from Remote Command Device.

  7. Click Add. The mirror to which the remote command device is assigned, is added to the Selected Mirrors table. If you want to remove the added mirror from the Selected Mirrors table, select the mirror and then click Remove.

  8. Click Finish.

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

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

  11. To check newly assigned remote command devices, see Remote Command Device in the Journal Volumes window.

    • If a remote command device is assigned to the mirror, the LDEV number is displayed.
    • If a remote command device is not assigned to the mirror, the field is blank.
    • If a remote command device cannot be assigned to the mirror, a hyphen is displayed.
Parent Topic
  • Delta resync configuration

    With the delta resync configuration, you bring the S-VOL to a consistent state more quickly after failure because only missing differential data must be copied.