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Resynchronize an ONTAP SnapMirror replication relationship

Contributors netapp-lenida netapp-aaron-holt netapp-dbagwell netapp-aherbin
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You need to resynchronize a replication relationship after you make a destination volume writeable, after an update fails because a common snapshot does not exist on the source and destination volumes, or if you want to change the replication policy for the relationship.

Beginning with ONTAP 9.8, you can use System Manager to perform a reverse resynchronization operation to delete an existing protection relationship and reverse the functions of the source and destination volumes. Then you use the destination volume to serve data while you repair or replace the source, update the source, and reestablish the original configuration of the systems.

Note

System Manager does not support reverse resynchronization with intracluster relationships. You can use the ONTAP CLI to perform reverse resync operations with intracluster relationships.
About this task

  • Although resync does not require a baseline transfer, it can be time-consuming. You might want to run the resync in off-peak hours.

  • Volumes that are part of a fan-out or cascade configuration can take longer to resynchronize. It is not uncommon to see the SnapMirror relationship reporting the status "preparing" for an extended time period.

  • Beginning with ONTAP 9.13.1, ONTAP attempts to use quick-resync by default to reduce resync time. The following conditions must be present for quick-resync to be used by default:

    • FlexVol volumes have no clones on the volume

    • When using the MirrorAllSnapshots policy

      Note Using -quick-resync can consume additional space on the resync destination volume due to removal of storage efficiency on transferred data blocks. This additional space consumption is recovered as part of the inline or post-replication storage efficiency application on the resync destination.

      The -quick-resync parameter is optional. You can enable or disable quick-resync by using the -quick-resync true|false parameter with the snapmirror resync command.

      For more information about -quick-resync, see the ONTAP command reference.

Steps

You can use System Manager or the ONTAP CLI to perform this task. If you use the ONTAP CLI, the procedure is the same regardless of whether you are making a destination volume writable or you are updating the replication relationship.

System Manager reverse resync

After you break a relationship to make a destination writable, reverse resynchronize the relationship:

  1. On the destination cluster, click Protection > Relationships.

  2. Hover over the broken off relationship you want to reverse, click Menu options icon, and select Reverse Resync.

  3. In the Reverse resync relationship window, click Reverse resync.

  4. Under Relationships, monitor the reverse resynchronization progress by viewing Transfer Status for the relationship.

Next steps

When the original source is available again, you can reestablish the original relationship by breaking the reversed relationship and performing another reverse resync operation. The reverse resync process will copy any changes from the site that is serving data to the original source and make the original source read-writable again.

System Manager resync

  1. Click Protection > Relationships.

  2. Hover over the relationship you want to resynchronize, and click Menu options icon and then select Break.

  3. When the relationship state displays "Broken off," click Menu options icon and then select Resync.

  4. Under Relationships, monitor the resynchronization progress by checking the relationship state. The state changes to "Mirrored" when resynchronization is complete.

CLI

  1. Resync the source and destination volumes:

    snapmirror resync -source-path <SVM:volume|cluster://SVM/volume> -destination-path <SVM:volume|cluster://SVM/volume> -type DP|XDP -policy <policy>
    Note You must run this command from the destination SVM or the destination cluster.

    The following example resynchronizes the relationship between the source volume volA on svm1 and the destination volume volA_dst on svm_backup:

    cluster_dst::> snapmirror resync -source-path svm1:volA -destination-path svm_backup:volA_dst

    Learn more about snapmirror resync in the ONTAP command reference.

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