2004-10-07 13:33:27

by Burke, Alan

[permalink] [raw]
Subject: NFS and/or autofs hanging on Linux

Hi Everyone,

We have got a problem with NFS hanging with automounter mounts.

We're running RH8 2.4.20-20.0 kernel
NFS-utils 1.0.1-2
Autofs4.1.2 (we must have the /net ability)
H/W is mixed HP4100's, Dell 2650's, Sun V60 and V65's
All the machines are in a Sun NIS domain with 700 Sun machines that run
fine.

The problem is intermittent; any automounter point can hang at any time.
For example auto_home may have 1000 entries
cd /home/user1 hangs and /home/user2 does not on machine Foo, but
/home/user2 is fine on machine Bar.

Once hung we sometimes can get it to release by umount -at nfs others
time a reboot is the only way to get it to release.

any help is appreciated

thanks,

alan



=20





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2004-10-11 22:09:52

by Goutham Kurra

[permalink] [raw]
Subject: Re: force unmount not working 2.4.22



I can see that '-f' tries to stop all active rpc tasks
to the server, but I guess the reference counts on the
mount are not dropped. What would be cool is a
'brute-force' option that kills any process that still
holds a reference to the filesystem and then also
unmounts it.

The problem with using something like fuser is that it
will promptly hang on an unreachable server making it
useless on nfs filesystems.

Any ideas on what to do in this case (i.e, unreachable
NFS server, plus a bunch of processes hung on the
mount)?

I'm uncomfortable using lazy unmounts as I don't have
a way of knowing if the filesystem has finally been
dropped or not.

goutham


--- Garrick Staples <[email protected]> wrote:

> On Sat, Oct 09, 2004 at 02:22:31PM -0700, Goutham
> Kurra alleged:
> >
> > Force unmount simply isn't working on a standard
> linux
> > 2.4.22 kernel. Isn't it supposed to unmount NFS
> > filesystems no matter what?
> >
> > In my case, the backend server is still up and
> > working, I have a "tail -f /mnt/nfs/foo" of some
> file
> > on the mount, and "umount -f" fails with "device
> or
> > resource is busy"
>
> I don't believe force is useful in this case, what
> you want is -l.
>
> -f Force unmount (in case of an unreachable
> NFS system). (Requires
> kernel 2.1.116 or later.)
>
> -l Lazy unmount. Detach the filesystem from
> the filesystem hierar-
> chy now, and cleanup all references to the
> filesystem as soon as
> it is not busy anymore. (Requires kernel
> 2.4.11 or later.)
>
> --
> Garrick Staples, Linux/HPCC Administrator
> University of Southern California
>

> ATTACHMENT part 2 application/pgp-signature





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2004-10-09 02:49:55

by Ian Kent

[permalink] [raw]
Subject: Re: NFS and/or autofs hanging on Linux

On Thu, 7 Oct 2004, Burke, Alan wrote:

> Hi Everyone,
>
> We have got a problem with NFS hanging with automounter mounts.
>
> We're running RH8 2.4.20-20.0 kernel
> NFS-utils 1.0.1-2
> Autofs4.1.2 (we must have the /net ability)
> H/W is mixed HP4100's, Dell 2650's, Sun V60 and V65's
> All the machines are in a Sun NIS domain with 700 Sun machines that run
> fine.

Have you patched the kernel with the latest autofs4 patches from
kernel.org?

You might like to visit Jeff Moyers people page at RedHat to get his
latest RPMS.

http://people.redhat.com/jmoyer

Ian



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2004-10-09 21:22:34

by Goutham Kurra

[permalink] [raw]
Subject: force unmount not working 2.4.22


Force unmount simply isn't working on a standard linux
2.4.22 kernel. Isn't it supposed to unmount NFS
filesystems no matter what?

In my case, the backend server is still up and
working, I have a "tail -f /mnt/nfs/foo" of some file
on the mount, and "umount -f" fails with "device or
resource is busy"

I notice that rpc_killall_tasks() is called from the
umount_begin(), but none of the processes get an EIO.
They continue to work as before.

I've also noticed this on stock RH 2.4.20-9 kernels.

Any idea what's going on?

Thanks!
g




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2004-10-09 21:42:49

by Garrick Staples

[permalink] [raw]
Subject: Re: force unmount not working 2.4.22

On Sat, Oct 09, 2004 at 02:22:31PM -0700, Goutham Kurra alleged:
>
> Force unmount simply isn't working on a standard linux
> 2.4.22 kernel. Isn't it supposed to unmount NFS
> filesystems no matter what?
>
> In my case, the backend server is still up and
> working, I have a "tail -f /mnt/nfs/foo" of some file
> on the mount, and "umount -f" fails with "device or
> resource is busy"

I don't believe force is useful in this case, what you want is -l.

-f Force unmount (in case of an unreachable NFS system). (Requires
kernel 2.1.116 or later.)

-l Lazy unmount. Detach the filesystem from the filesystem hierar-
chy now, and cleanup all references to the filesystem as soon as
it is not busy anymore. (Requires kernel 2.4.11 or later.)

--
Garrick Staples, Linux/HPCC Administrator
University of Southern California


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