Unmounting a file system after NFS export

Because NFS use of a GPFS file system might result in a file being held, attempting to unmount a GPFS file system might return a Device is busy error. If this occurs, stop the NFS daemons before attempting to unmount the file system at the NFS server.

For KNFS on Linux®, issue this command:
```
/etc/rc.d/init.d/nfs stop
```
On AIX®, issue this command:
```
stopsrc -g nfs
```

NFS can be restarted after the unmount completes.

For KNFS on Linux, issue this command:
```
/etc/rc.d/init.d/nfs start
```
For AIX, issue this command:
```
startsrc -g nfs
```