[Gluster-users] Protocol stacking: gluster over NFS

harry mangalam harry.mangalam at uci.edu
Mon Sep 17 18:00:14 UTC 2012

Just to clarify, we are using the native kNFS-server from the distro, not 
gluster's NFS implementation.  Note that CentOS 5.7/5.8 does not seem to 
support this kind of loopback mounting with the kNFS version they use (kNFS 
ver 1.0.8/9). 

However, the recent kNFS servers from Ubuntu/Debian (kNFSv 1.2.0) and SL 6.2 
(1.2.3) do support it.  We're still testing but have not yet found the kind of 
deadlocks/crashes that others have mentioned with the gluster NFS (touch 


On Monday, September 17, 2012 09:08:08 AM Jeff White wrote:
> I was under the impression that self-mounting NFS of any kind (mount -t
> nfs localhost...) was a dangerous thing.  When I did that with gNFS I
> could cause a server to crash in no time at all with a simple dd into
> the mount point. I was under the impression that kNFS would have the
> same problem though I have not tested in myself (this was discussed in
> #gluster on irc.freenode.net some time ago).  I'm guessing this would be
> a bug in the kernel.  Has anyone seen issues or crashes with locally
> mounted NFS (either gNFS or kNFS)?
> Jeff White - GNU+Linux Systems Administrator
> University of Pittsburgh - CSSD
> On 09/14/2012 03:22 PM, John Mark Walker wrote:
> > A note on recent history:
> > 
> > There were past attempts to export GlusterFS client mounts over NFS, but
> > those used the GlusterFS NFS service. I believe this is the first
> > instance "in the wild" of someone trying this with knfsd.
> > 
> > With the former, while there was increased performance, there would
> > invariably be race conditions that would lock up GlusterFS. See the
> > ominous warnings posted on this Q&A thread:
> > http://community.gluster.org/a/nfs-performance-with-fuse-client-redundanc
> > y/
> > 
> > I am curious to see if using knfsd, as opposed to GlusterFS' NFS service,
> > yields a long-term solution for this type of workload. Please do continue
> > to keep us updated.
> > 
> > Thanks,
> > JM
> > 

Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine
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