*BSD News Article 75952


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From: tedm@agora.rdrop.com
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: How can I "defrag" my hard drive?
Date: 12 Aug 1996 05:27:21 GMT
Organization: Symantec Corporation
Lines: 37
Message-ID: <4umfbp$ftl@symiserver2.symantec.com>
References: <32010808.ABD@ctcc.gov.za> <01bb8100$0be8a640$0f02000a@jamesben> <Pine.LNX.3.91.960811210449.5303A-100000@gallup.cia-g.com>
Reply-To: tedm%toybox@agora.rdrop.com
NNTP-Posting-Host: 198.6.34.2
X-Newsreader: IBM NewsReader/2 v1.2

In <Pine.LNX.3.91.960811210449.5303A-100000@gallup.cia-g.com>, Stephen Fisher <lithium@cia-g.com> writes:
>

[question about fragmentation deleted]

>
>These file fragments are not the same as a fragmented DOS FAT drive. =20
>They do not hender performance like a dos fragmented drive.
>

If your definition of "disk fragmentation" is what the DOS-community's
definition is, in other words the disk has to do excessive seeking to
get the parts of a file together, then you shouldn't worry about it in
most cases.

The FreeBSD filesystem, just like the HPFS, NTFS and other advanced
filesystems is _resistant_ to file fragmentation.  Resistance does not equal
immunity, however.

If you run your disk partitions about 70% full or less you will not have to
worry about file fragmentation with an advanced filesystem.  This is because
the filesystem will tend to keep the file parts together on the disk.

However, if you run 99% or 100% full disk, like a number of servers that
I know, then over time your disk will get badly fragmented.  The only way
to correct this is to delete 20% of your files, and either backup to tape and
restore, or run a script that copies and moves files around repeatedly.  The
reason that nobody does this is most people just buy larger disks.

(after all, the 5th law of computing states that files on a computer will
expand over time to fill all available disk space :-))

Ted
tedm@agora.rdrop.com