quota / block

Hi all,
I have a dedicated serveur gentoo.

I enconter problems managing disk quotas.

I thought that hard limit was in Mo, but it's obviously "blocks"
But trying to evaluate the size of a block give me unexpexted results:


1_ How can i know the size of my blocks??
i know 2 commands:
$$$> edquota username
and $$$> du /home/userdir

user1:
edquota gives me 156212 blocks
and du /home/user1 : 8 920 (Mo)
thus a block size is about: 8920 (000) / 156 212 == 57 o / block

user2:
edquota gives me 367 372 blocks
and du /home/user2: 28 964 (Mo)
thus a block size is here: 28 964 (000) / 367 372 == 78 o /block

What is the relation between "block" and disk usage????

How can i manage my disk quota in Mo.

This is a big problem because when quota exeeds, any file uploaded is
set to 0ko and erase the existing file. And all internet website goes wrong.



Thanks for help.