Failed to change NetApp volume to data-protection (volume busy)

This relationship had been intentionally broken for some testing on the destination volume and when resync was issued, it had failed due to volume busy.

                            Healthy: false
                   Unhealthy Reason: Scheduled update failed to start. (Destination volume must be a data-protection volume.)
           Constituent Relationship: false
            Destination Volume Node: 
                    Relationship ID: aa9b0b54-64d9-11e5-be3f-00a0984ad3aa
               Current Operation ID: 1bed480d-1554-11e7-aa85-00a098a230de
                      Transfer Type: resync
                     Transfer Error: -
                   Current Throttle: 103079214
          Current Transfer Priority: normal
                 Last Transfer Type: resync
                Last Transfer Error: Failed to change the volume to data-protection. (Volume busy)

To check the snapshots on the volume for busy status and dependency:
snapshot show -vserver 'vserver_name' -volume 'volume_name' -fields busy, owners  

In this case, a running NDMP backup session was preventing the resync.

To list NDMP backup sessions:
system services ndmp status  

The system services ndmp status command lists all the NDMP sessions in the cluster. By default it lists the following details about the active sessions:

To list details for a NDMP backup session:
system services ndmp status -node 'node_name' -session-id 'session-id'  

From here you can confirm this is the NDMP session you need to kill by referencing the ‘Data Path’ field. This should be the path to the volume that is failing the resync.

To kill NDMP backup session:
system services ndmp kill 'session-id' -node 'node_name'  

The system services ndmp kill command is used to terminate a specific NDMP session on a particular node in the cluster. This command is not supported on Infinite Volumes.

After clearing the busy snapshot application dependency, I was able to successfully issue the resync as per normal operations.