NFS mounts can be tricky. After an NFS request times out, NFS request are retried indefinitely by default. This can lead to unexpected hangs on the client. (1)
Use the mount option
soft to limit the number of retries to 3.
If an NFS share hangs, it can be unmounted as follows: Find the mount point using
mount and then
umount -f -l [mount point] (
-f for force and
-l for lazy unmount, i.e. detach now and cleanup references later) (2)
grep -L [string] [files](e.g.
grep -L foo *)
wipefs -a /dev/sd[x](1)