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Date:      Tue, 03 Nov 1998 14:28:11 -0800
From:      Eric Hodel <hodeleri@seattleu.edu>
To:        Graeme Tait <graeme@echidna.com>, freebsd-questions@FreeBSD.ORG
Subject:   Re: File system performance
Message-ID:  <363F837B.2F4BF749@seattleu.edu>
References:  <363F7AA3.22254A9C@echidna.com>

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Stabbing in the dark, but the interleave on the SCSI drive may not be
optimized for the small 1k files you use.  To do this you would have to
do a low-level format of you SCSI drive, then reinstall your software. 
Read the manual or contact Seagate to see if a low-level format is
allowed for your drive, I've heard that it can trash some types of
drives.

Graeme Tait wrote:
> 
> I have a situation that involves manipulating large numbers of small
> files of about 1k each. I recently noticed a strange performance
> comparison between my "play" system (a 486-DX2/66/16MB with
> run-of-the-mill IDE drives and a Promise caching controller, running
> 2.2.6R) and "production" system (Pentium-II/400/256MB with Ultra 2 LVD
> SCSI and 4.5GB Seagate Cheetah drives, running 2.2.7S/CAM).
> 
> When deleting these files (rm -rf), the 486 does it with a minimum of
> fuss (no trashing of the disk heads) at about 120 files a second. Disk
> operations occur ever second or so with intervals between.
> 
> The production system only manages about 40 files a second, and you can
> hear that the disk heads are going for their life, vibrating back and
> forth between tracks. It's impressive to hear the speed of the head
> positioning, but the end result is hardly so.
> 
> In both cases, the files being deleted were expanded from the same
> archive, into a relatively empty filesystem (built with the default
> fragment size, etc.).
> 
> Similar behaviour occurs when the gzipped archive is expanded, but in
> this case the systems are about equal in speed.
> 
> In other filesystem comparisions, with larger files, the production
> system runs rings around the test system, as you would expect.
> 
> What is happening here? Is maybe something configured wrong on the
> production system?
> 
> --
> Graeme Tait - Echidna
> 
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