[DRBD-user] Mirroring between NFS servers

Kelsey Cummings kgc at corp.sonic.net
Fri Oct 26 18:47:23 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Fri, Oct 26, 2007 at 05:54:38PM +0200, Bernd Schubert wrote:
> On Friday 26 October 2007 16:51:00 Andreas Haase - evolver group wrote:
> > On Fri, 26 Oct 2007, Mark Watts wrote:
> > > DRBD could be used as the backing store for an HA NFS pair, but I
> > > believe NFS clients would have to reconnect on fail-over since
> > > file-handle state is stored in memory, not on disk.
> >
> > you can replace /var/lib/nfs by a sombolic link to a directory inside your
> > drbd filesystem. Then switching over to standby node is possible without
> > remounting filesystems from nfs clients. Depending on used hardware it
> > could also be necessary to provide as fsid in /etc/exports.
> In principle not neccessary any more with linux-2.6.x, you need to have 
> mounted /proc/fs/nfsd.  

What do you mean by 'in principle' not neccessary anymore with 2.6?  I've
just finished an active/active NFS cluster with DRBD and heartbeat and had
trouble with 'stale nfs filehandles' until I moved the nfs state dir to
something inside the export.

> The only trouble you still have are these rpc.statd / lockd information 
> in /var/lib/nfs/sm, I think these still should be equal on both servers, but 
> locking information are not part of the NFS protocol (e.g. RFC 1813) up to 
> v3.

No locking here, so that's not a problem for my application.

Kelsey Cummings - kgc at corp.sonic.net      sonic.net, inc.
System Architect                          2260 Apollo Way
707.522.1000                              Santa Rosa, CA 95407

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