Re: Problem using exportfs in an active-active nfs cluster

Neil Brown
2010-06-08T21:54:32Z

On Tue, 08 Jun 2010 18:24:48 +0200
RaSca <rasca-9B074fXSGsOr88ip1nKoZ2D2FQJk+8+b@public.gmane.org> wrote:

> Hi all,
> I'm trying to use a resource agent named exportfs for my active-active
> nfs cluster configuration.
> The resource agent works using the exportfs command. I have an instance
> of nfs-kernel-server for each node and exportfs dynamically remove or
> append the export to the node (obviously I've got also a shared storage).
> The problem comes when the export is mounted by a client and this client
> is writing on it: if the node switches, then the migration fails. The
> sequence is this one:
>
> - The resource exportfs stops correctly (the Resource Agent launch
> exportfs -u)
> - The Filesystem resource tries to unmount the exported filesystem,
> doing an fuser to see if some processes are locking the fs.
> - fuser doesn't return anything, but the filesystem is still locked.
> This happens because the kernel process nfsd is locking the FS.
> - The migration fails.
>
> The only way to make thing work again is to restart the
> nfs-kernel-daemon on the node which the resource reside and then cleanup
> the resource.
>
> Now, after many discussions on the Linux-ha Mailing List, I'm here to
> ask if this problem is about the exportfs command. Why a filesystem
> remains locked to the nfsd kernel process even if I (or the resource
> agent) have done an "exportfs -u" command?
>
> What can else I do to free the exported filesystem? Note that I've tried
> to mount from the client with "nolock" option and also the exported
> filesystem is mounted with "noatime".
>
> Thanks a lot,
>

Try
exportfs -f

NeilBrown