I've recently had to deal with a pesky, intermittent NFS client/server hung mount point issue. When the problem occurs on the client I cannot unmount, along with some other odd behavior. The only immediate resolution I have to date is to reboot the client box.
shutdown -r now does not work at all. I've since discovered
reboot -f, which does reboot the system. Why? I've read the man pages but nothing seems to answer my question.
shutdown -r now behave differently than
(I'm continuing to resolve the NFS issue, but that is not my question here.)