storing mail across several cyrus partitions

[Vincent Fox]

>> May somebody recommend reliable/safe filesystem that support resizing?
>> I'm afraid to use anything except ext3 in production enviroment...
>>     

Forgot to mention for ZFS, you can grow the pool by adding disks to it.
We run a pool full of mirror pairs so we'd add more pairs.

Quite easy and can be done while online.  The stripe width dynamically
adjusts to needs and what disks are in the pool.  There is also no need to
determine inode settings, as the metadata is dynamic and uses empty space
in the pool.  As long as you have space in the pool, there is no limit 
on number
of files.  So far as I have looked, what tuneable parameters there are 
can all
be done while hot.

We use the compression feature on our mail pool which gains us 1.28x the
space for a little more CPU usage.   Also we keep 14 daily of snapshots in
the pool so recovering a users mailbox usually doesn't involve going to 
tape.