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

[Neil Brown <neilb@suse.de>]

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