Busy NFS device - what's causing it?

[Bob McClure Jr]

On Tue, Aug 02, 2005 at 10:34:29AM -0700, Mark Knecht wrote:
> Hi,
>    This is jsut a generic question since the list has been pretty
> quiet. At time I'll want to unmount a volume. For instance, this
> morning I'm messing around a bit with mount options and I want to see
> what happens when I try a new option from the command line. However I
> cannot unmount the volume to try mounting it:
> 
> dragonfly ~ # umount /video
> umount: /video: device is busy
> umount: /video: device is busy
> dragonfly ~ #
> 
>    Generically, how do I determine why a device is 'busy'? If the
> system thinks it's busy I assume it keeps that state somewhere. Is it
> available to me to read? When I grep mtab I see this:
> 
> dragonfly ~ # cat /etc/mtab | grep video
> myth14:/video /video nfs
> rw,noexec,nosuid,nodev,_netdev,addr=192.168.1.14,addr=192.168.1.14 0 0
> dragonfly ~ #
> 
> ...telling me where it's located but it doesn't tell me who's using
> it. I happen to know that the only valid user of this partition is
> mythbackend which I've shut down, but I still cannot unmount it.
> 
>    So, how do I find what's keeping the partition busy?
> 
> Cheers,
> Mark

The tool you want is fuser (as in file user).  I've not used it much,
so "man fuser" for details.

Because I have multiple xterms up, I frequently find that I've left a
session sitting somewhere in that filesystem.  But there have been
times that fuser didn't report anything and I never did figure out
what the problem was.

Cheers,
-- 
Bob McClure, Jr.             Bobcat Open Systems, Inc.
robertmcclure at earthlink.net  http://www.bobcatos.com
God doesn't have (or need) a Plan B.