[Dovecot] Compressing existing maildirs

[Jan-Frode Myklebust]

On Wed, Dec 28, 2011 at 03:56:33PM -0800, Dovecot-GDH wrote:
> The cleanest (though not necessarily simplest) way to go about this would be to use dsync to create a new maildir and incrementally direct traffic to a separate Dovecot instance.
> 
> Unless you have a legacy application that relies on maildir, switching to mdbox would be a good idea too.

We just got rid of the legacy app that worked directly against the
maildirs, which is the reason we now can turn on compression. I
intend to switch to mdbox, but first I need to free up some disks by
compressing the existing maildirs (12 TB maildirs, should probably
compress down to less than half).

> 
> I expect that with Dovecot compression is something that can "just be turned on", but for fear of any possible issue, I chose to migrate mailboxes in batches with the way mentioned above.
> 

Migrating to mdbox is much scarier to me than an easily reversible
compression of existing maildir files.

Could you please give a bit more details about how you did this migration?
Did you change user home dirctory in the process? Seeing the scripts you
used to run the migration would be very interesting..


  -jf