[Gluster-users] NFS file locking with gluster 3.7.3

[Niels de Vos]

On Wed, Aug 05, 2015 at 04:11:47PM +0100, Thibault Godouet wrote:
> Looking around I get the impression that file locking (NLM) may simply not
> be supported in glusterfs's built-in NFS server.

This is actually supported. But note that you can not run a userspace
NLM implementation provided by a NFS-server (Gluster/NFS or NFS-Ganesha)
on a system that acts as an NFS-client. The Linux kernel NFS-client uses
the lockd kernel module, and there can be only one NLM implementation be
registered at rpcbind. Whichever service (nfs-client or nfs-server)
starts first, will be able to register itself, the 2nd one will (mostly
silently) fail.

> I get the impression that Ganesha is aimed at supporting NFS better, and
> presumably supports locking well, so I should give it a try (If I
> understand well the performance is also likely to be higher, which is a
> nice bonus!)

NFS-Ganesha offers more features than Gluster/NFS. The performance is
highly dependent on the workload, Gluster/NFS can be faster for many of
them.

Cheers,
Niels


> 
> If someone could confirm this that would be useful to make sure I'm going
> in the right direction.
> 
> Thanks,
> Thibault.
> On 4 Aug 2015 1:23 pm, "Thibault Godouet" <tibo92 at godouet.net> wrote:
> 
> > Hi,
> >
> >
> >
> > I have a cluster of 2 servers running 3.7.3 with replication, and standard
> > NFS (no ganesha).  This in on CentOS 6.
> >
> > I use CTDB with 2 virtual IPs (one for each server in a normal
> > situation) to share the volume over NFS and CIFS (samba).
> >
> >
> >
> > fnctl() file locking doesn't seem to work when the volume is mounted over
> > NFS.
> >
> > This is apparent with a 'svn info' (svn 1.8 if it made any difference) in
> > a local working copy:
> >
> >
> >
> > $ svn info
> > svn: E200033: Another process is blocking the working copy database, or
> > the underlying filesystem does not support file locking; if the working
> > copy is on a network filesystem, make sure file locking has been enabled on
> > the file server
> > svn: E200033: sqlite[S5]: database is locked, executing statement 'PRAGMA
> > synchronous=OFF;PRAGMA recursive_triggers=ON;PRAGMA foreign_keys=OFF;PRAGMA
> > locking_mode = NORMAL;'
> >
> >
> >
> > a strace shows:
> >
> >
> >
> > $ svn info
> > svn: E200033: Another process is blocking the working copy database, or
> > the underlying filesystem does not support file locking; if the working
> > copy is on a network filesystem, make sure file locking has been enabled on
> > the file server
> > svn: E200033: sqlite[S5]: database is locked, executing statement 'PRAGMA
> > synchronous=OFF;PRAGMA recursive_triggers=ON;PRAGMA foreign_keys=OFF;PRAGMA
> > locking_mode = NORMAL;'
> >
> >
> >
> > Everything seems to work fine on native Gluster (FUSE) mounts: the same
> > 'svn info' works nicely.
> >
> > I can't really use native mounts due to the performance hit (many small
> > files) and the fact I would need to install the gluster client software on
> > every server.
> >
> >
> >
> > Is fnctl() file locking supported in Gluster NFS mounts?  If so, any idea
> > why it doesn't work for me?
> >
> >
> >
> > Thanks,
> >
> > Thibault.
> >

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