File system fails to unmount

There are indications leading you to the conclusion that your file system cannot unmount and takes a course of action to correct the problem.

Those indications include:

Return codes or error messages indicate the file system does not unmount.
The mmlsmount command indicates that the file system is still mounted on one or more nodes.
Return codes or error messages from the mmumount command.

If your file system does not unmount, then follow these steps:

If you get an error message similar to:
```
umount: /gpfs1: device is busy
```
the file system does not unmount until all processes are finished accessing it. If mmfsd is up, the processes accessing the file system can be determined. See The lsof command. These processes can be killed with the command:
```
lsof filesystem | grep -v COMMAND | awk '{print $2}' | xargs kill -9 
```
If mmfsd is not operational, the lsof command is not able to determine which processes are still accessing the file system.

For Linux® nodes it is possible to use the /proc pseudo file system to determine current file access. For each process currently running on the system, there is a subdirectory /proc/pid/fd, where pid is the numeric process ID number. This subdirectory is populated with symbolic links pointing to the files that this process has open. You can examine the contents of the fd subdirectory for all running processes, manually or with the help of a simple script, to identify the processes that have open files in GPFS file systems. Terminating all of these processes may allow the file system to unmount successfully.
To unmount a CES protocol node, suspend the CES function using the following command:
```
mmces node suspend
```
- Stop the NFS service using the following command:
```
mmces service stop NFS
```
- Stop the SMB service using the following command:
```
mmces service stop SMB
```
- Stop the Object service using the following command:
```
mmces service stop OBJ
```
Verify that there are no disk media failures.
Look on the NSD server node for error log entries. Identify any NSD server node that has generated an error log entry. See Disk media failure for problem determination and repair actions to follow.
If the file system must be unmounted, you can force the unmount by issuing the mmumount -f command:
Note:
1. See File system forced unmount for the consequences of doing this.
2. Before forcing the unmount of the file system, issue the lsof command and close any files that are open.
3. On Linux, you might encounter a situation where a GPFS file system cannot be unmounted, even if you issue the mmumount -f command. In this case, you must reboot the node to clear the condition. You can also try the system umount command before you reboot. For example:
```
umount -f /fileSystem 
```
If a file system that is mounted by a remote cluster needs to be unmounted, you can force the unmount by issuing the command:
```
mmumount fileSystem -f -C RemoteClusterName
```