NFS Services Administrator's Guide

Configuring and Administering NFS
Configuring and Administering an NFS Server
Chapter 2 35
If your NFS server will be down for only a very short period of time, this
procedure is not necessary. If the server is down for only a few minutes,
and directories are hard-mounted on the clients, clients attempting
access to the server will simply hang until it comes back up. Then, they
will resume access to it as if nothing had happened.
However, if the server will be down for a long time, NFS clients
attempting access to it will have to interrupt their attempts, usually
with [CTRL]-C. If directories are mounted with the nointr option,
clients must reboot their systems in order to stop trying to access a down
server.
See the following man pages for more information: showmount(1M),
fuser(1M), exportfs(1M), and mountd(1M).