handling unresonsive NFS servers

[Rick Macklem]

On Wed, 25 Jul 2007, Jim Rees wrote:

> 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.

Linux has something called a "lazy" umount, which I think is similar to 
the above, except that it is invoked by a sysadmin instead of a timeout
(and doesn't come back, just umounts when the RPCs finally happen). I
didn't see much use in it, but I can see that setting a mount point
"not working for now" might be useful.

>
> And by all means, do fix umount -f.
>