[Lustre-discuss] (no subject)

[Hayes, Robert N]

We will test the mem=12G suggestion. Before attempting the 1.8.0 client, can you confirm that a 1.8 client should work with a 1.6 server without causing any more complications?

/bob

-----Original Message-----
From: Andreas.Dilger at sun.com [mailto:Andreas.Dilger at sun.com] On Behalf Of Andreas Dilger
Sent: Monday, May 11, 2009 1:54 PM
To: Hayes, Robert N
Cc: lustre-discuss at lists.lustre.org
Subject: Re: [Lustre-discuss] (no subject)

On May 11, 2009  13:35 -0700, Hayes, Robert N wrote:
> While performing a single copy, single client write/read test using dd,
> we find that our Nehalem clients running 2.6.18-92.1.10.el5-lustre-1.6.5.1
> write about half the speed of our Nehalem clients running
> 2.6.18-53.1.13.el5_lustre.1.6.4.3 to three different lustre file systems.

> This is true even though the slower clients have the same processors and
> more RAM, 18GB for the slow writers and 12GB for the fast writers. Both
> systems use OFED 1.3.1. All benchmarks we use perform better on the
> slow-write clients and read speed from LFS is comparable across all
> clients.

Have you tried booting the slower-with-more-RAM clients using "mem=12G"
to see if the performance gets worse with more RAM?  There is a known
performance bottleneck with the client-side cache in 1.6 clients, and
you may be triggering this...

If you have the luxury to do so, testing a 1.8.0 client's IO performance
against the same filesystems would also determine if the client-side
cache performance fixes therein will already solve your problems.

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