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From: brtmac@maverick.ksu.ksu.edu (Brett McCoy)
Newsgroups: comp.unix.admin,comp.unix.questions,sussex.general,comp.misc
Subject: Re: Disc (De)Fragger
Keywords: Disc Fragmentation
Message-ID: <1991May2.024639.9011@maverick.ksu.ksu.edu>
Date: 2 May 91 02:46:39 GMT
References: <4973@syma.sussex.ac.uk> <1991May01.154043.1031@scuzzy.in-berlin.de>
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In <1991May01.154043.1031@scuzzy.in-berlin.de> src@scuzzy.in-berlin.de (Heiko Blume) writes:

>stevedc@syma.sussex.ac.uk (Stephen Carter) writes:
>>		Disc Fragmentation (etc)

>for system V machines:
>i regularly use a program called packdisk on my /usr/spool/news.
>another program called fsanalyze tells me that the above filesystem
>takes about two weeks to develop >40% fragmentation. packdisk makes
>that ~3% again. packdisk was posted to comp.sources.misc, volume8,
>fsanalyze is in volume5. of course packdisk is somewhat dangerous :-)

One reason such a tool doesn't exist for BSD 4.2 filesystems is that
it is built in to the filesystem.  The 4.2 filesystem does it's best
to keep a disk from fraging, and to unfrag a disk that is fragmented
as files are read and then rewritten.  The 10% diskspace buffer that
is suggested for filesystems is to allow the extra space with which
to perform this task.  If you cut the buffer down to 0% and then fill
the disk up it will fragment rather badly, but so long as you leave
the 10% free space you will usually never get more than 3-4%.  On
my news partition the worst I have ever seen it get is 4% after months
of use.

--
Brett McCoy			Computing and Telecommunications Activities
brtmac@maverick.ksu.ksu.edu	Kansas State University
Every woman's a 10.  It just depends upon which base you're counting in.