[Gluster-devel] What functionality is expected from persistent NFS-client tracking?

[Anand Avati]

On Wed, Feb 6, 2013 at 9:19 AM, Niels de Vos <ndevos at redhat.com> wrote:
>
> > Oh, OK.  Looking at the code in xlators/nfs/server/src/nlm4.c....  Looks
> > like it's probably just using the same statd as the kernel server--the
> > one installed as a part of nfs-utils, which by default puts its state in
> > /var/lib/nfs/statd/.
> >
> > So if you want failover to work, then the contents of
> > /var/lib/nfs/statd/ has to be made available to the server that takes
> > over somehow.
>
> This statd data and the implementation of the NLM protocol is not
> something I am very familiar with. But Rajesh (on CC) explained a little
> about it and informed me that the current NLM implementation indeed does
> not support transparent fail-over yet.
>
>
The NLM implementation in gluster is stateless for all practical reasons
(all locks are translated to lk() FOPs on the bricks). However we just use
/ depend on the RHEL rpc.statd -- which is not clustered. If the RHEL
rpc.statd is replaced with a "clustered" statd, Gluster's NLM should "just
work" even in failovers (by making a failover appear as a server reboot and
kick off NLM's lock recovery) -- which may not be ideal and efficient, but
should be functional.

Avati
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