Disk I/O Performance

[Mike Horwath]

On Tue, Oct 19, 2004 at 04:02:41PM -0500, Kristofer Pettijohn wrote:
> On Tue, Oct 19, 2004 at 04:45:03PM -0300, Jo?o Carlos Mendes Lu?s wrote:
> >     I'd say that you have to check which CCD chunk size is best for 
> > your needs.  The manual for vinum recommends avoiding chunk sized to a 
> > power of two, which is probably the first big mistake of everybody.
> 
> I've tried a wide range of chunk sizes, from 128kB to 64MB.. also have
> been avoiding powers of 2.

The old idea from someone long ago was to set the stripe size the size
of the cylinder block.  I found 8MB to be pretty decent, though not
perfect.

> >     Try mounting with option noatime, if you haven't already.  And use 
> > the largest block size possible when formatting.  Last time I read about 
> > there was a limit of 16384, but I would expect better performance for 
> > large file with 64k blocks (and 8k frags).
> 
> The largest block size is 64k, and I have done that as well.

Use this for tunefs - it made a little bit of a difference:

	tunefs -m 8 -o time /dev/something

and make sure you set up the dspool.ctl file correctly because of the
change.

-- 
Mike Horwath, reachable via drechsau at Geeks.ORG