AppSync: A UNIX-based copy may encounter the error: "Failed to unmount the copy with error"

The mount host in use is the AIX host.

Unmount operation does not complete with the below events:

<DATE & TIME>,Unmount Copy,33a8372e-915d-4122-a8a7-4021dc89255c,MILE_000005,<AppSync Server>,Unmount Copy phase for <service plan> completed with errors
<DATE & TIME>,Unmount Copy,33a8372e-915d-4122-a8a7-4021dc89255c,VM_000073,d<AppSync Server> ,Failed to unmount the copy with error: Unmount operation failed. Make sure the filesystem(s) are not in use.

In the server log, see that the unmount failed exception followed by an unmount request that is sent to the host and a response received.

<DATE & TIME> ERROR [Thread-412 (ActiveMQ-client-global-threads)] [com.emc.archway.commands.serviceplan.workflow.WorkflowDeployPhaseCommandBean] [AppSync Server] [] 614a4cfc-c3fb-4ec8-85f6-b29a7c6047d5->>> Exception Occurred: UnmountFailedException, Message: Unmount operation failed.

The agent log shows the below:

<DATE & TIME> acputil.py[671]:execute() Info:Running command: umount <File System >
<DATE & TIME> host.py[3919]:unMount() error: ['umount: error unmounting [Device]: Device busy']
<DATE & TIME> host.py[3920]:unMount() errorcode: 1
<DATE & TIME> host.py[3921]:unMount() Info:couldn't unmount the filesystem <File System>
<DATE & TIME> host.py[3926]:unMount() Info:FileSystem is busy, can't unmount the file system
<DATE & TIME> host.py[3812]:unmountFilesystem() error:
<DATE & TIME> host.py[3915]:unMount() Info:Running umount command ['umount', '/ora/oemxxx/xxxxx']
<DATE & TIME> host.py[3847]:unmountFilesystem() Info:Some of the filesystems couldn't be Unmounted, so can't deport the VG <VG Name>

During the unmount operation, the file system was in use.

Go to the mount host. Run fuser command to determine what process or application holds the file system.
Engage the UNIX Administrator for assistance if need be.

Once determined, wait for it to finish or stop or kill that process or application to release the file system.
Then rerun the unmount operation. It succeeds.