Re: Huge linux/ext3 fragmentation in /var/spool/mail using wu-imapd; seeking filesystem recommendation

From: Dances With Crows (danSPANceswitTRAPhcrows_at_gmail.com)
Date: 04/27/05 

Date: Wed, 27 Apr 2005 12:17:25 -0500

[ IMAP group removed ]
["Followup-To:" header set to comp.os.linux.misc.]
On Wed, 27 Apr 2005 16:44:22 +0000 (UTC), essteeaenn@worldbadminton.com
staggered into the Black Sun and said:
> In comp.os.linux.misc cdr@stolaf.edu <cdr@stolaf.edu> wrote:
>> Does anyone have a recommendation for either a better way to defrag or
>> for a superior filesystem type that is less susceptible to
>> fragmentation?
> If you ignore the Linux acolytes who maintain that fragmentation
> (a) doesn't exist
> (b) can happen but is a "good" thing

The people who claim that fragmentation is less of a problem than you
may think have a point. Unix-like systems are multi-user and
multi-process, and Linux itself is very aggressive about disk caching,
so when any process reads a file, that file is stuck in cache. The next
process that needs that file reads it from cache, not disk, so
fragmentation only matters on the first read. If you have problems with
the speed of disk I/O, faster disks or more RAM may help more than
trying to defragment things.

Peter T. Breuer has written on this topic in the past; groups.google for
his name and keyword "fragmentation", read what he's said, and address
his points and/or rebut them before you do anything else.

> then you'll find that there are tools for some FS types like EXT2/EXT3
> but not for others. The only universal way to defrag that I'm aware of
> is the backup/wipe/restore method that you used.

> look for "defrag", which works for EXT2/EXT3. Anyone know of more
> general defrag tools?

"Backup, mkfs, restore" is the most general way. Any defrag tool *must*
be filesystem-specific for obvious reasons. If there's any defrag tool
for ReiserFS 3.6, I haven't heard of it. 

-- 
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /    mail: TRAP + SPAN don't belong
http://www.brainbench.com     /                Hire me! 
-----------------------------/ http://crow202.dyndns.org/~mhgraham/resume

Relevant Pages

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