[gpfsug-discuss] GPFS samba config

Jonathan Buzzard jonathan at buzzard.me.uk
Wed Dec 4 12:13:08 GMT 2013

On Wed, 2013-12-04 at 11:37 +0000, Orlando Richards wrote:
> On 03/10/13 10:23, Jonathan Buzzard wrote:
> > There are a couple of
> > other options as allowSambaCaseInsensitiveLookup and
> > syncSambaMetadataOps but I have not determined exactly what they do...
> Hi JAB - I think I've figured out what syncSambaMetadataOps does - I 
> think it's a performance optimsation for the vfs_syncops module. With 
> syncSambaMetadataOps set, you can then set:
>   syncops:onmeta = no
> I found this in:
> http://sambaxp.org/fileadmin/user_upload/SambaXP2011-DATA/day2track1/SambaXP%202011%20Ambach%20Dietz.pdf
> under "metadata synchronization performance" (slides 21 & 22) referred 
> to as the mysterious "new (internal) GPFS parameter"
> Of course, since it's undocumented this is purely guesswork on my part - 
> would be good to get confirmation from IBM on this.

That's a really good catch, and the only one of the magic levers I had
no real idea what it was doing. The allowSambaCaseInsensitiveLookup is
easy, it is basically getting the file system to do the matching when
you have "case sensitive = no" in your smb.conf, rather than Samba
trying lots of combinations. What I don't have a handle on is what the
performance benefit for setting it is.

I am working up on doing testing on what the samba ACL's do. My
hypothesis is that it makes the NFSv4 ACL's follow NTFS schematics. This
should be relatively easy to test.

> Also - I'd love to get the output of "testparm -v" and "mmfsadm dump 
> config" from an IBM SONAS cluster node to see what the best practise 
> GPFS + samba settings are. Any chance of that from an IBMer?

I don't think that will work. Try flipping some of the magic levers on a
test cluster and you will see what I mean. Basically they don't show up
in the output of mmfsadm dump :-(


Jonathan A. Buzzard                 Email: jonathan (at) buzzard.me.uk
Fife, United Kingdom.

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