handling unresonsive NFS servers

[Jim Rees]

Afs has the same problem, and solves it by marking a server "down" when it
doesn't respond.  The timeout is very long, like a minute or more.  Normally
this would permanently hang the client, but once the server is marked down,
any subsequent operations fail immediately.  The client checks periodically
to see if the server has come back up.  Failing this way is better than
waiting forever, because waiting forever results in a reboot when the
machine's owner runs out of patience.

And by all means, do fix umount -f.