Running the clients and servers on the same machine might actually
hurt your performance a bit.  Since PVFS doesn't have a native
quadrics method, maybe you save a lot of overhead skipping the
tcp-over-quadrics stuff.

Yeah but I wasn't running over the quadrics I was using the
gig-ethernet however the data should be using the loopback then going
right to disk... One of these days we'll get an infiniband box we can
test on ;)

It might be easier to see patterns if you held servers constant and
increased the number of clients, or held clients constant while
varying numbers of servers.  To visualize both you'd end up with a
3-d plot...

That'd be interesting but where would the data go for the odd clients
as you get more clients than servers? and how would you control that
to make the graph make sense?

I'm looking at 255-test.csv.  That's 256 nodes (acting as servers and
clients), each client running dd to write 10 GB to a single server?

Yeah each client dd'd a 10Gb file to itself through pvfs.

I don't know why that workload would take about a minute for up to 64
clients, speed up for 65-141 clients, and then go back to being slower
for the rest of the runs, except for a cluster of fast runs at 173-183
clients.

Since you've got things set up so each client talks to a single server
locally, we shouldn't be seeing network contention or switch
wierdness.  Since you have a single client talking to a single server,
the access pattern from each client should look pretty regular to
pvfs2-server.   The tight bimodal distribution of results suggests...
I don't know... fortunate placement of files on the storage device for
some runs? http://www.coker.com.au/bonnie++/zcav

Well we ran on top of the xfs filesystem which normally gets about
300Mb/s to its raid5 set, and if it was fortunate placement of the
files then wouldn't it be more random, instead of bimodal?

Thanks,
- David Brown
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