Resynchronizing GAD pairs

While the GAD pairs are being suspended, the storage system on the primary site does not execute update copy operation towards the secondary volume. When the pairs are resynchronized, only the accumulated differential data after suspension is updated to the secondary volume, and the secondary volume would have the same data as the primary volume again. After that, the update copy operation starts again towards the secondary volume.

For details about registering pairs to a consistency group during resync, see Registering pairs to a consistency group from the secondary storage system.

TipWhen the secondary volume is located in the local storage system, if you want to register GAD pairs to a consistency group, perform the following procedure:
  1. In the storage system in which the secondary volume is located, resynchronize the pairs without specifying the consistency group ID. If you resynchronize a pair in the storage system in which the secondary volume is located, the primary volume and the secondary volume are reversed (swap resynchronization).
  2. Suspend the GAD pair in the storage system in which the primary volume (the secondary volume before swap resynchronization) is located.
  3. In the storage system in which the primary volume is located, specify the consistency group ID to resynchronize the pair.

Before you begin

  • Storage Administrator (Remote Copy) role is required.
  • In the Remote Replication window or the View Pair Properties window, the pair status must be PSUS, PSUE, or SSWS.

    If the pair status is PSUS or PSUE, the pair can be resynchronized only when the I/O mode is Local. If the pair status is SSWS, the primary volume and the secondary volume are reversed and then the pair is resynchronized (swap resync).

Procedure

  1. In the Storage Systems tree, select Replication, and then Remote Replication.

  2. In the GAD Pairs tab, select the pair you want to resync, and then click Resync Pairs.

  3. Check that the pair you want to resync is displayed in the Selected Pairs table.

  4. In Copy Pace, specify the maximum number of tracks to be copied in a single remote I/O. The default is 15 (fast copy pace). To change the copy pace, enter a number from 1 to 4:

    • The speed of 1 is a slow copy pace, and is used to reduce impact on host I/O.
    • The speeds of 2 and 3 are a medium copy pace.
    • The speed of 4 is a fast copy pace, and the host I/O performance might be degraded.

    If you enter a number from 5 to 15, the speed of 4 (fast copy pace) is used.

  5. Select CTG ID. You can select this only if the primary volume is located in the local storage system.

  6. Select ALUA Mode.

  7. Click Finish.

  8. In the Confirm window, check the settings you made, and then enter the task name in Task Name.

  9. Click Apply.

    The task is registered. The Tasks window appears if the Go to tasks window for status check box is selected.

Next steps

After resynchronizing a pair, in the Remote Replication window, check that the GAD pair is correctly displayed (in PAIR status).

To check the status of a pair that is being resynchronized, click the Refresh button at the top right corner in the main window of Device Manager - Storage Navigator, or display detailed information in the View Pair Properties window.

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