[Ocfs2-users] Recommended block size for a mail environment

[jab at ufba.br]

Hello all,

I have a mail environment, with a situation seemed with a previous  
mail "Different size with du and ls". My environment is:

Debian Etch 4.0
Postfix 2.3.8-2
ocfs2-tools 1.2.1-1.3
kernel 2.6.18-4-amd64

My "df -h" shows me the follow:

df -Th
/dev/sdb1    ocfs2    1,0T  894G  131G  88% /mails

df -Thi
File Syst.   Type      Inodes   IUsed IFree IUse% Mount on
/dev/sdb1    ocfs2       16M     14M    2,1M   88% /mails

but when I do a "du -sh . /mails" it shows me 480GB, so much different  
from 849G. The OCFS2 block size is 4K. I made a script to average the  
medium mail size, and it's the follow:

0k to 1k - 8%
0k to 2k - 13%
0k to 3k - 22%
0k to 4k - 35%
4.1k to 6k - 15%
6.1 to 8k - 10%
8.1k to 10k - 9%
10.1k to 12k - 7%
rest - 24%

My debug.ocfs2 doesn't has the "-R" option:

# debugfs.ocfs2 -R "stats" /dev/sdb1
debugfs.ocfs2: invalid option -- R
debugfs.ocfs2 1.2.1


My doubts are:

4k is a good block size for this situation?
How to avoid waste space as now (~50%)?
If I choose to use 2k, will the available Inodes double (16M to 32M)?

Thanks a lot!

Jeronimo

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