dovecot - May 2009 - ext3/ext4 performance issue

Wonder if anyone else has actually noticed this and has some kind of
statistics?

http://marc.info/?t=124234003300001&r=1&w=2

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* Timo Sirainen <tss at iki.fi>:
> Wonder if anyone else has actually noticed this and has some kind of
> statistics?
> 
> http://marc.info/?t=124234003300001&r=1&w=2
I could run stats here, with 12.000 users to see what the average size
is...


-- 
Ralf Hildebrandt
Postfix - Einrichtung, Betrieb und Wartung       Tel. +49 (0)30-450 570-155
http://www.computerbeschimpfung.de
"People demand freedom of speech as a compensation for the freedom of
thought which they seldom use."

on 5-15-2009 11:59 AM Timo Sirainen spake the following:
> Wonder if anyone else has actually noticed this and has some kind of
> statistics?
> 
> http://marc.info/?t=124234003300001&r=1&w=2
> 
One could always run the mailstore on LVM and then you could snapshot the
mount and then fsck it while still technically in use. It would probably slow
down the filesystem, but it is still live.

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On Fri, 15 May 2009, Timo Sirainen wrote:

on my production system, I've scanned 97559 dirs in total, including 
'tmp's, Maildir & homedirs. Control and Indexes are located
elsewhere.

There a total of 97406, 5238 of them use more than one block, hence,
92168 are skipped from the stats below.

Then I compared the size of the directory file with this:

filename size    sum of length of all entries in the directory
   + 10 * number of entries in the directory

The ratio is calculated:
  size of directory file divided by filename size

ratio	num of
 	dirs
<2	1593
3	810
4	228
5	129
6	122
7	65
8	56
9	31
10	30
11	27
12	21
13	18


Top ranks are:
fnamsiz dirsiz ratio
23	1417216	61618.09
23	1089536	47371.13
23	872448	37932.52
23	839680	36507.83
23	802816	34905.04
23	684032	29740.52
23	684032	29740.52
23	655360	28493.91
70	1847296	26389.94
23	593920	25822.61
23	581632	25288.35
23	536576	23329.39
23	532480	23151.3
23	516096	22438.96
23	503808	21904.7
23	471040	20480
23	446464	19411.48
23	425984	18521.04
287	5005312	17440.11
23	376832	16384

There are 2175 dirs with a ratio >= 10.

There are 1613 directories with a ratio >= 100,
747	"/cur"
492	"/new"
372	"/tmp"
1	Maildir itself
1	.dovecot.rawlog

Nearly all of them are: INBOX, Trash & SPAM folders.  The two last ones
with various names depending of the IMAP client used.

I used this Perl script:
http://www2.inf.fh-brs.de/skdata/dovecot/cntDirsize.bz2

Bye,

- -- 
Steffen Kaiser
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