Resynchronizing pairs

You resynchronize TrueCopy pairs when you recover data from a disaster or when you perform tasks on TrueCopy pairs, like assigning pairs to consistency groups.

While a TrueCopy pair is split, the primary system does not perform update copy operations to the S-VOL. Resynchronizing the pair updates the S-VOL with differential data accumulated since the split, so that its data is again identical with the P-VOL's data. Update copy operations begin again to the S-VOL.

When resynchronizing, TrueCopy pairs can be migrated to global-active device. See the global-active device User Guide.

Before you begin

  • Required role: Storage Administrator (Remote Copy)
  • Required status: Both volumes must be suspended (PSUS or PSUE).
  • This operation is performed from the primary system only.

In RAID Manager, use the pairresync command.

Procedure

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

  2. In the Storage Systems tree, click Replication Remote Replication.

  3. In the Remote Replication window, click the TC Pairs tab, and then select the pair to be resynchronized.

  4. In the TC Pairs tab, click Resync Pairs.

  5. In the Resync Pairs window, ensure that the pair to be resynchronized appears in the Selected Pairs table.

  6. For Primary Volume Fence Level, specify whether the primary system rejects write operations to the P-VOL when the pair is split due to an error.

    • Status: The P-VOL cannot be written to only if the primary system is not able to change S-VOL status to Suspend.
    • Never: The P-VOL can always be written to.
    • Data: The P-VOL cannot be written to when the update copy fails.

    For more information, see the planning section on fence level options in the TrueCopy User Guide.

  7. For Copy Pace, specify the number of tracks to be copied per remote I/O during the operation. The default is 15 (fast copy pace). This option affects performance as follows:

    • For OPEN-V, 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.
    • Other than OPEN-V, to change the copy pace value, enter a number from 1 to 15.
      • The speeds of 1 to 5 are a slow copy pace, and are used to reduce impact on host I/O.
      • The speeds of 6 to 10 are a medium copy pace.
      • The speeds of 11 to 15 are a fast copy pace, and the host I/O performance might be degraded.

  8. For Copy Priority, enter the priority, or scheduling order, for the resync operation. You can set priority from 1 to 256. The default is 32. For more on priority, see the descriptions in the planning section on priority settings for initial copy operations in the TrueCopy User Guide.

  9. Click Finish.

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

  11. Click Apply to save your settings.

    After the pair is resynchronized, make sure that the TrueCopy pair is displayed correctly (in the PAIR status) in the Remote Replication window.

    To check the pair resynchronization operation status, click the update button at the upper right corner of the Device Manager - Storage Navigator main window to update the information in the Remote Replication window, or view the detailed status information in the View Pair Properties window.

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