When NCP Server is active, it always keeps a file open on a volume. As a result, issuing dismount, umount, or delete commands for an NSS volume fails, whether the command is issued from the command line, in NSSMU, or in iManager.
This occurs because Linux does not allow you to dismount a volume if a file is open on that volume. Linux does not provide a method of identifying which files are open on volumes.
To dismount or delete an NSS volume on your OES 2015 SP1 server:
At the server prompt, open the NCP Console by entering
ncpcon
Dismount the volume from NCP.
The volume is no longer accessible or visible to NCP clients.
In iManager, dismount or delete the volume, as desired.