[Lustre-devel] LustreFS performance

Andreas Dilger adilger at sun.com
Mon Mar 2 12:45:01 PST 2009

On Mar 02, 2009  20:04 +0300, Vitaly Fertman wrote:
>    RAM: enough to have a tmpfs for MDS;
Note that strictly speaking we need to use ldiskfs on a ramdisk, not
tmpfs, because we don't have an fsfilt_tmpfs.

> Q:  which raid?
> A: raid5, as it seems to be the most popular.

I would propose:
- for MDT it needs to be RAID-1+0, because of small, random IO sizes
- for OST it needs to be RAID-6, because of double-failure risk (see
  Lustre Manual "RAID" section for discussion)

> **** Statistics ****
> During all the tests the following is supposed to be running on all  
> the servers:
> 1) vmstat
> 2) iostat, if there is some disk activity.
> smth else?

I would propose either LLNL's LMT or HP's collectl, which both also
collect Lustre stats.  Those both provide more information than the
above, and having the IO/CPU load correlated to Lustre RPC counts is
very useful.

> Q: do we want to test stat(2) with other then tmpfs disk on OST?
> what journal should it have if so?

I would be quite interested in the performance numbers from just
the ramdisk MDT+OST, to see what the upper limit of the protocol
and network are.

> 9. find
> Q: despite the fact we currently have a large downgrade with
> "find -f type", do we want to have this test in the general test set?

Some of that performance loss should have been fixed recently.  We
should continue to test it.

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

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