size of folder on disk much larger than size reported by mail client.

[Warren Howard]

Hi,

I've noticed that the size of the folders on disk can be much larger
than the size reported by the mail client and I'm wondering why.

I'm using Cyrus-imapd 2.2.12 and the mail client is Squirrelmail 1.4.8
with the 1.5 version of the Folder Sizes plug-in.

In Squirrelmail I can use the Folder Sizes plug-in to show that I have a
folder with a "count" of 17120 and a size of 68 MB.  The folder is a
shared folder that goes by the name "Postfix users".  On the mail server
the corresponding disk location (to the best of my knowledge) for this
folder is "/var/spool/imap/p/Internet\ Mailing\ Lists/Postfix\ users/".

This directory has 17123 files in it, exactly 17120 (the count reported
by the Folder Sizes plug-in) plus three additional files cyrus.cache,
cyrus.header and cyrus.index.  The size of this directory with the three
additional "cyrus" files is 120 MB - almost twice the size reported by
the Folder Sizes plug-in for Squirrelmail.  Now cyrus.cache is 24 MB and
cyrus.index is 1 MB (cyrus.header is tiny 165 bytes), subtracting these
leaves me with mail message files that add up to 95 MB still 27 MB
larger than what is reported by the Folder Sizes plug-in.

I also checked the size of the "Postfix users" using cyradm (in case the
Folder Sizes plug-in was wrong).

localhost> info 'Internet Mailing Lists/Postfix users'
{Internet Mailing Lists/Postfix users}:
  lastupdate: 14-Sep-2006 10:35:00 +0530
  partition: default
  size: 72033301

so why does cyradm and the Folder Sizes plug-in report a size of 68 MB
where if I go and check on disk I see the sum of the message files on
disk is closer to 95 MB?

Is it a file system thing?  I'm using reiserfs with the following fstab
options

/dev/system/var         /var            reiserfs        notail,noatime  0 0

I'm worried that "notail" and lots of small message files is chewing up
disk space could it be the case?


Thanks,


Warren.