If programs hang doing file-related work, the NFS server may have crashed. The following message may appear on the machine's console:
NFS server sys_name not responding, still tryingThe message includes the name of the NFS server that is down. This is probably a problem either with one of the NFS servers or with the network.
If a client machine completely stops responding, check the servers from which the filesystems were mounted. If one of them is down, client machines may wait indefinitely. When the server comes back up, programs continue automatically and are unaffected.
When there are network or server problems, programs that access hard-mounted remote files fail in different ways from those that access soft-mounted remote files. Hard-mounted remote filesystems cause programs to retry until the server responds again, while soft-mounted remote filesystems return errors after a certain number of retries.
Once a hard mount succeeds, programs that access hard-mounted files hang as long as the server fails to respond. You may wish to specify the keyboard interruptible option when hard-mounting filesystems from an unreliable server; this allows you to interrupt the remote mount operation and returns an error message from the server.
If a soft-mounted server dies, other work should not be affected. Programs that time out trying to access soft-mounted remote files will fail and receive an error message, but it should still be possible to get work done on other filesystems.