[Gluster-users] Tuning for small files

Tue Sep 29 17:36:20 UTC 2015

Ben,

I suspect meta-data / 'ls -l' performance is very important for my svn
use-case.

Having said that, what do you mean by small file performance? I thought
what people meant by this was really the overhead of meta-data, with a 'ls
-l' being a sort of extreme case (pure meta-data).
Obviously if you also have to read and write actual data (albeit not much
at all per file), then the effect of meta-data overhead would get diluted
to a degree, bit potentially still very present.

Would there be an easy way to tell how much time is spent on meta-data vs.
Data in a profile output?

One thing I wonder: do your comments apply to both native Fuse and NFS
mounts?

Finally, all this brings me back to my initial question really: are there
any tuning recommendation of configuration tuning for my requirement (small
file read/writes on a pair of nodes with replication) beyond the thread
counts and lookup optimize?
Or are those by far the most important in this scenario?

Thx,
Thibault.
----- Original Message -----
> From: hmlth at t-hamel.fr
> To: abauer at magix.net
> Cc: gluster-users at gluster.org
> Sent: Monday, September 28, 2015 7:40:52 AM
> Subject: Re: [Gluster-users] Tuning for small files
>
> I'm also quite interested by small files performances optimization, but
> I'm a bit confused about the best option between 3.6/3.7.
>
> Ben Turner was saying that 3.6 might give the best performances:
> http://www.gluster.org/pipermail/gluster-users/2015-September/023733.html
>
> What kind of gain is expected (with consistent-metadata) if this
> regression is solved?

Just to be clear, the issue I am talking about is metadata only(think ls -l
or file browsing).  It doesn't affect small file perf(well not that much,
I'm sure a little, but I have never quantified it), with server and client
event threads set to 4 + lookup optimize I see between a 200-300% gain on
my systems on 3.7 vs 3.6 builds.  If I needed fast metadata I would go with
3.6, if I need fast smallfile I would go with 3.7.  If I needed both I
would pick the less of the two evils and go with that one and upgrade when
the fix is released.

-b

>
> I tried 3.6.5 (last version for debian jessie), and it's a bit better
> than 3.7.4 but not by much (10-15%).
>
> I was also wondering if there is recommendations for the underlying file
> system of the bricks (xfs, ext4, tuning...).
>
>
> Regards
>
> Thomas HAMEL
>
> On 2015-09-28 12:04, André Bauer wrote:
> > If you're not already on Glusterfs 3.7.x i would recommend an update
> > first.
> >
> > Am 25.09.2015 um 17:49 schrieb Thibault Godouet:
> >> Hi,
> >>
> >> There are quite a few tuning parameters for Gluster (as seen in
> >> Gluster
> >> volume XYZ get all), but I didn't find much documentation on those.
> >> Some people do seem to set at least some of them, so the knowledge
> >> must
> >> be somewhere...
> >>
> >> Is there a good source of information to understand what they mean,
> >> and
> >> recommendation on how to set them to get a good small file
> >> performance?
> >>
> >> Basically what I'm trying to optimize is for svn operations (e.g. svn
> >> checkout, or svn branch) on a replicated 2 x 1 volume (hosted on 2
> >> VMs,
> >> 16GB ram, 4 cores each, 10Gb/s network tested at full speed), using a
> >> NFS mount which appears much faster than fuse in this case (but still
> >> much slower than when served by a normal NFS server).
> >> Any recommendation for such a setup?
> >>
> >> Thanks,
> >> Thibault.
> >>
> >>
> >>
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