[Lustre-discuss] (no subject)

[Andreas Dilger]

On May 11, 2009  14:38 -0700, Hayes, Robert N wrote:
> 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?

Yes, the 1.8.x clients are interoperable with 1.6.x servers.  If you are
worried about testing this out during live system time then you can wait
for an outage window to test the 1.8 client in isolation.  There is
nothing to do on the server, and just RPM upgrade/downgrades on the client.

> -----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.

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