[Gluster-users] Migrate from an NFS storage to GlusterFS

Stephan von Krawczynski skraw at ithnet.com
Tue Feb 16 13:53:10 UTC 2010

On Tue, 16 Feb 2010 17:31:00 +0530
Vikas Gorur <vikas at gluster.com> wrote:

> Olivier Le Cam wrote:
> > Thanks Vikas. BTW, might it be possible to have the same volume 
> > exported both by regular-NFS and GlusterFS at the same time in order 
> > to migrate my clients smoothly? Is there any risks to get GlusterFS 
> > confused and/or the ext3 volume damaged?
> That would be quite risky. If you have both GlusterFS clients and NFS 
> clients operating on
> the same files or directories there are chances of race conditions which 
> might lead
> to lost files, GlusterFS getting confused, NFS getting confused etc. I 
> wouldn't recommend it.

But isn't that a setup that every average user would expect to work? You can
share data between nfs and a local (nfs-server) user, too. Is your file
locking racy? Did you break atomic operations?

Remember that long discussion about soft migrating data by just exporting
already existing data via glusterfs without copying? This point is very
similar. It is a common understanding in modern fs that multiple users of the
same file should be managed by record- and/or file-locking. A network based fs
on top of some other fs should behave just as it were some average local user
- then your data should (and must) be safe.

> Vikas


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