[Cluster-devel] Re: [NFS] [PATCH 0/4 Revised] NLM - lock failover
Marc Eshel
eshel at almaden.ibm.com
Wed Apr 25 15:21:57 UTC 2007
nfs-bounces at lists.sourceforge.net wrote on 04/25/2007 07:10:31 AM:
> J. Bruce Fields wrote:
> > On Thu, Apr 05, 2007 at 05:50:55PM -0400, Wendy Cheng wrote:
> >
> >> 1) Failover server exports filesystem with "fsid" option as:
> >> /etc/exports entry> /mnt/shared/exports *(fsid=1234,sync,rw)
> >> 2) Failover server dispatch rpc.statd with "-H" option.
> >> 3) Failover server drops locks based on fsid by:
> >> shell> echo 1234 > /proc/fs/nfsd/nlm_unlock
> >> 4) Takeover server enters per fsid grace period by:
> >> shell> echo 1234 > /proc/fs/nfsd/nlm_set_igrace
> >> 5) Takeover server notifies clients for lock reclaim by:
> >> shell> /usr/sbin/sm-notify -f -v floating_ip_address -P
an_sm_directory
> >>
> >
> > I don't understand statd and lockd as well as I should. Where exactly
> > does the takeover server stop serving requests, and the failover
server
> > start? If this isn't done carefully, you can leave a window between
> > steps 3 and 4 where a client could acquire a lock before its rightful
> > owner reclaims it, right?
> >
> >
> The detailed overall steps were described in the first email we sent
> *long* time (> 6 months, I think) ago. The first step of the whole
> process is tearing down the floating IP from the failover server. The IP
> is not accessible until filesystem is safely fail-over and SM_NOTIFY
> ready to be sent.
I thought this is a solution for an active active server where a cluster
file system can export the same file system from multiple NFS servers.
Marc.
>
> Last round of discussion gave me an impression that as long as I rebased
> the code into akpm's mm tree, these patches would get accepted. So I
> have been quite careless in this submission and just realized people
> have a very short memory :) .. Will do the write-up and put it somewhere
> so we don't need to go thru this again.
>
> -- Wendy
>
>
>
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