[Beowulf] Iozone on a Cluster

[Egan Ford]

Find a parallel shell (e.g. pdsh), then write a script to run iozone,
something like:

echo ready
while [ ! -r /other/nfs/fs/go ]
do
	sleep .1
done
cd /nas/fs
iozone option option option ... >/other/nfs/fs/iozone.$(hostname -s).out
exit 0

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 ...
do
ssh $i script &
done;wait;date >>foo

then type:

touch /other/nfs/fs/go

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..
> Thanks!
> Dan
> 
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