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Date: Thu, 28 Aug 2003 18:22:17 -0700
From: David Schultz <das@FreeBSD.ORG>
To: Claus Guttesen <cguttesen@yahoo.dk>
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Subject: Re: Some additional tests run on my performance testing
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On Thu, Aug 28, 2003, Claus Guttesen wrote:
> So I newfs'ed it with 8 and 16 kb blocksize did an
> import of a 1.5 GB pg-dump.
> 
> > numbers you suggest above, I loaded a DB with 8k and
> > 16K blocks
> > (translation: almost all write activities).
> > 
> > them to stay about the same across the board.  If
> > someone wants to do
> > some good read tests, I'd be interested in those
> > results.
> > 
> 
> The 8 kb blocksize took 60 min. to import, and the 16
> kb ditto took 45 min. So I'm settling on 16 kb blocks.

Note that doing sequential reads and writes is VERY different from
doing random reads and writes.  In the former case, a larger
filesystem block size may reduce fragmentation and help you, but
in the latter case---specifically for writes---you're doing twice
the I/O due to the larger filesystem blocks.  Your import and
Bill's tests fall into the first category.  It would be
interesting to see what sort of performance you get under a real
workload.