ONTAP 9.14

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Recover from automatic unplanned failover operations

An automatic unplanned failover (AUFO) operation occurs when the primary cluster is down or isolated. The ONTAP Mediator detects when a failover occurs and, and executes an automatic unplanned failover to the the secondary cluster. The secondary cluster is converted to the primary and begins serving clients. This operation is performed only with assistance from the ONTAP Mediator.

After the automatic unplanned failover, it is important to rescan the host LUN I/O paths so that there is no loss of I/O paths.

Reestablish the protection relationship after an unplanned failover

You can reestablish the protection relationship using ONTAP System Manager or the ONTAP CLI.

ONTAP System Manager
  1. Navigate to Protection > Relationships and wait for the relationship state to show “InSync.”

  2. To resume operations on the original source cluster, click kabob icon and select Failover.


You can monitor the status of the automatic unplanned failover using the snapmirror failover show command.

For example:

ClusterB::> snapmirror failover show -instance
Start Time: 9/23/2020 22:03:29
         Source Path: vs1:/cg/scg3
    Destination Path: vs3:/cg/dcg3
     Failover Status: completed
        Error Reason:
            End Time: 9/23/2020 22:03:30
Primary Data Cluster: cluster-2
Last Progress Update: -
       Failover Type: unplanned
  Error Reason codes: -

Resume protection in a fan-out configuration after failover

If you experience a failover on the secondary cluster in the SM-BC relationship, the asynchronous SnapMirror destination becomes unhealthy. You must manually restore protection by deleting and recreating the relationship with the asynchronous SnapMirror endpoint.

  1. Verify the failover has completed successfully:
    snapmirror failover show

  2. On the asynchronous Snapmirror endpoint, delete the fan-out endpoint:
    snapmirror delete -destination-path destination_path

  3. On the third site, create an asynchronous SnapMirror relationships between the new SM-BC primary volume and the async fan-out destination volume:
    snapmirror create -source-path source_path -destination-path destination_path -policy MirrorAllSnapshots -schedule schedule

  4. Resynchronize the relationship:
    snapmirror resync -destination-path destination_path

  5. Verify the relationship status and heath:
    snapmirror show

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