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[Cluster-devel] Re: [NFS] [PATCH 0/4 Revised] NLM - lock failover



nfs-bounces 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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