[Lustre-discuss] Benchmarking small file performance

[Balagopal Pillai]

On Sat, 17 May 2008, Andreas Dilger wrote:
I don't have the numbers anymore, i did the benchmark almost an year ago
to decide between gfs and lustre. I remember when the filesize was close 
to 1 MB, the performance of lustre started picking up and became closer 
to gfs and nfs. The default file size of postmark is quite small, more in line with a regular 
maildir setup 
and text only emails. The lru size also had an effect and once that is 
bumped up, as mentioned in the manual and wiki, the number of files that 
is used by postmark can be increased without a big penalty. In the 
default settings for very small files, the results are worse than nfs.
Lustre could still be a good choice for mail servers that use mbox, but 
for maildir i am not so sure.

Regards
Balagopal 


> On May 17, 2008  13:47 -0300, Balagopal Pillai wrote:
> > On Sat, 17 May 2008, Ragnar Kjørstad wrote:
> >      Postmark is a good benchmark for small file peformance. I have tried 
> > it with gfs and lustre before for comparison. Lustre doesn't shine well in 
> > that benchmark. But when the file size is set a little high, lustre does pick 
> > up quite a bit.
> 
> Do you have numbers at what file size Lustre does well with postmark?
> Given HTML email with large attachments, the days that average email
> size for many users is getting quite large.
> 
> > > On Thu, May 15, 2008 at 04:21:56PM -0400, Rick Friedman wrote:
> > > > We build a Lustre appliance that comes fully configured and tuned. A
> > > > number of customers have asked us about small file performance. We are
> > > > looking for feedback on how people "quantify" this type of performance
> > > > with their Lustre based systems. In most cases we are looking at
> > > > applications that are reading and writing files in the 1K to 20M size
> > > > range. 
> > > 
> > > One tool commonly used to compare file system operation performance for
> > > local filesystems and NFS clients is bonnie++
> > > (http://www.coker.com.au/bonnie++/). It's not really designed for
> > > paralell filesystems but at least it will quantify single-client lustre
> > > performance in a way that your customers can relate to. 
> > > 
> > > Note that since bonnie++ only runs on a single machine at the time you
> > > need some kind of wrapper to run it on a multi-client lustre cluster.
> > > There is a very primitive one available at
> > > http://ragnark.vestdata.no/download/dbonnie++.txt, but what you should
> > > do is make a version of bonnie++ that use MPI for syncronization instead
> > > of semaphores, so that it can easily be run on clusters.
> 
> 
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
>