Your comment about dd means that at least some part of your file system is set up to stripe across multiple OSTs, but my first guess on hearing this would be that IOZone is working in a space where the default striping is left at 1.  Itís the simplest explanation, though that doesnít mean itís right. :)

- Patrick

From: "E.S. Rosenberg" <esr+hpdd-discuss@mail.hebrew.edu>
Date: Thursday, February 20, 2014 at 8:01 AM
To: "hpdd-discuss@lists.01.org" <hpdd-discuss@lists.01.org>
Subject: [HPDD-discuss] iozone and lustre

Hi all,
When I run the iozone benchmark on lustre it ends up only using one OSS server, I assume this has something to do with the way it writes but I'm not really sure where to look, at the moment I am just using automated tests...

(iozone -Ra -g 64G)

lustre is functioning fine and when using dd from multiple machines with a bs=102400 it uses all OSS.

Any pointers would be very welcome...