The unmount command makes the contents of a user-defined file system (UDFS) inaccessible to the integrated file system interfaces.
The objects in a UDFS will not be individually accessible once the UDFS is unmounted. The Remove Mounted File System (RMVMFS) or UNMOUNT commands will make a mounted file system inaccessible to the integrated file system namespace. If any of the objects in the file system is in use (for example, a file is opened) at the time of using the command, you will receive an error message. The UDFS will remain mounted. If you have mounted over any part of the UDFS, then this UDFS cannot be unmounted until it is uncovered.
For example, you mount a UDFS /dev/qasp02/jenn.udfs over /home/judy in the integrated file system namespace. If you then mount another file system /pubs over /home/judy, then the contents of jenn.udfs will become inaccessible. Furthermore, you cannot unmount jenn.udfs until you unmount the second file system from /home/judy.