[PVFS-users] Poor performance

[Robert Latham]

On Tue, Jun 07, 2005 at 10:06:38AM +0100, Jon Combe wrote:
> The file is 1549403622 bytes. As far as I can see (via top) nothing
> else is happening on the box.

Comparing the time to operate on 1.5 GBytes locally vs. operating on that
same 1.5 GBytes remotely isn't exactly a fair comparison.   Perhaps I'm
making a bad assumption about your topology, but you have clients and
servers on separate machines, right?  If so, there's no way around the
fact you have to move 1.5 GBytes over the network in the pvfs case.
 
> Well thats fair enough, but are you saying the sort of performance
> difference I'm seeing above is normal for PVFS?

With the large blocksizes you were seeing just over 10 Mbytes/sec.
that's pretty resaonable for single-node access to PVFS over fast
ethernet.  That's pretty close to the maximum bandwidth you'll get out
of fast ethernet.  With the default blocksize you were still getting 3
MBytes/sec.   I think that's pretty typical performance for small
blocksize transfers over ethernet.  

Like I said, I don't know the exact details of your setup, so let me
know if i've gone off on a faulty assumption here. 

==rob

-- 
Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA                B29D F333 664A 4280 315B