[Lustre-discuss] Quota performance

[Andreas Dilger]

On Sep 24, 2008  06:11 -0400, Mag Gam wrote:
> I was wondering if we should implement quotas for our students but is
> there a downside such as performance? Previously, we implemented
> quotes using vxfs and we noticed a significant performance hit and the
> users were not happy. So, are there any downsides such as performance
> loss when using quotas?

There is defitely some performance overhead for quotas.  I don't have
a number offhand.  The actual performance overhead depends on how hard
you are pushing the network/filesystem already - if the IO rates aren't
extreme then the network quota overhead probably isn't too bad.

The quota for Lustre is designed to be high performance, with some
sacrifice to the accuracy of the quota.  It isn't really designed to
handle tiny quotas (like 50MB/user), if that is your target.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.