dovecot - Jun 2010 - Question about directory hashing

Hello

     I have been reading http://wiki.dovecot.org/MailLocation and 
http://wiki.dovecot.org/Variables and I do not fully understand the 
directory hashing feature. I want to migrate > 70.000 users from Sun 
Messaging to Dovecot using imapsync. I have tested with 
mail_location=maildir:/buzones/us.es/%1Hu/%2.1u/%n but I get the 
following directory tree:

`-- 0
     |-- -
     |-- 1
     |-- 2
     |-- 3
     |-- 8
     |-- _
     |-- a
     |-- ab
     |-- b
     |-- c
     |-- d
     |-- e
     |-- ev
     |-- f
     |-- g
     |-- h
     |-- i
     |-- ie
     |-- is
     |-- j
     |-- jb
     |-- jj
     |-- jp
     |-- js
     |-- k
     |-- l
     |-- m
     |-- mb
     |-- n
     |-- o
     |-- p
     |-- pp
     |-- q
     |-- r
     |-- rm
     |-- s
     |-- t
     |-- u
     |-- v
     |-- w
     |-- x
     |-- y
     `-- z

     The ideal directory layout should be the following:

     First directory level: Letters from a to z
     Second directory level: Numbers from 0 to 200
     Third directory level: %n (username without @domain)

     How can I achive this directory layout (or other optimized for 
70.000 users) . I use ext3 on Red Hat Enterprise Linux 5 with directory 
indexes on.

     Regards

     Javier de Miguel

On pe, 2010-06-11 at 08:16 +0200, Javier de Miguel Rodr??guez wrote:
> mail_location=maildir:/buzones/us.es/%1Hu/%2.1u/%n but I get the 
> following directory tree:
> 
> `-- 0
>      |-- -
>      |-- 1
>      |-- 2
..

Numbers with %H work in a special way (actually I had completely
forgotten about this):

%H - take a 32bit hash of the variable and return it as hex. You can
also limit the hash value. For example %256Hu gives values 0..ff. You
might want padding also, so %2.256Hu gives 00..ff. This can be useful
for example in dividing users automatically to multiple partitions.
>      The ideal directory layout should be the following:
> 
>      First directory level: Letters from a to z
>      Second directory level: Numbers from 0 to 200
>      Third directory level: %n (username without @domain)
That's not possible, but you could have the same number of directories
with: %2.26Hn/%2.200Hn/%n