[Bioclusters] Tool to benchmark disk IO?

[James Cuff]

On Fri, 2004-09-24 at 14:32, James Cuff wrote:
> On Fri, 2004-09-24 at 14:21, Dan Bolser wrote:
> > On Fri, 24 Sep 2004, elijah wright wrote:
> 
> > Seeker 1...Seeker 3...Seeker 2...start 'em...done...done...done...
> >               -------Sequential Output-------- ---Sequential Input--
> > --Random--
> >               -Per Char- --Block--- -Rewrite-- -Per Char- --Block---
> > --Seeks---
> > Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> >           100  4240 25.9  5437  2.1  4780  2.4 19595 100.1 566942 99.7 2023.0 10.1
> > 
> > With default file size (104857600). The CPU is 'amazingly high' during
> > reads.
> 
> I think your file size is to small - 100MB will fit in the UBC.  Once
> written according to these figures you are seeing ca 600MB/s reads for
> getchar ops.  The block ops must not be htting the buffer cache
> correctly so go back down to 2MB/s.  This seems pretty poor even for

Doh!  That should have been 20MB/s for getchar and 566MB/s for blocks. 
Sorry - I said I had too much coffee :-)  Anyway the take home message
is still the same - make the file size at least 2x the amount of memory
in your server.

Cheers,

j.