[Beowulf] Iozone on a Cluster
egan at sense.net
Thu Jan 5 18:54:00 EST 2006
Find a parallel shell (e.g. pdsh), then write a script to run iozone,
while [ ! -r /other/nfs/fs/go ]
iozone option option option ... >/other/nfs/fs/iozone.$(hostname -s).out
Use pdsh or other to run the script on all nodes, e.g.:
date >foo;pdsh ...;date >>foo
Poor man parallel shell example:
date >foo;for i in node1 node2 node3 ...
ssh $i script &
I do not recommend summing the output of iozone when running in parallel.
If you have a lot of clients they will not all start at the same time, some
may block on I/O for some period of time before starting inflating the
performance. It is better to do the math yourself by using the timestamps
in the foo file.
A better solution to all of this is to use iometer. With iometer you launch
a daemon on each node, then startup a iometer GUI (on Windows). The GUI can
contact all the daemons and coordinate a benchmark in parallel, isolating
read from write. With iozone in parallel you may get read and write
overlap. You will need to patch iometer to use a directory instead of the
root of the FS or all daemons will try to read/write the same name. I have
a patch somewhere to use a shell variable.
Another solution would be to use an MPIIO benchmark.
Normally I only use iozone for testing individual drive performance on nodes
and then check for a normal distribution. I use MPIIO benchmarks and
iometer for testing SAN, NAS, and Parallel file systems.
> -----Original Message-----
> From: beowulf-bounces at beowulf.org
> [mailto:beowulf-bounces at beowulf.org] On Behalf Of
> Daniel.G.Roberts at sanofi-aventis.com
> Sent: Wednesday, January 04, 2006 2:18 PM
> To: beowulf at beowulf.org
> Subject: [Beowulf] Iozone on a Cluster
> Can any one pass along some knowledge of how they ran iozone
> on a linux cluster?
> I am trying to pin down a NAS storage on my cluster and I am
> wondering on how to leverage Iozone to identify problems..
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