[Dovecot] Compressing existing maildirs

[Jan-Frode Myklebust]

On Thu, Dec 29, 2011 at 07:00:03AM -0600, Stan Hoeppner wrote:
> > 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).
> 
> How much additional space do you expect the conversion process to
> compressed mdbox to consume?

Somewhere around 1/3 of the current usage, I expect..

> It shouldn't need much.  Using dsync, the
> conversion will be done one mailbox at a time and the existing emails
> will be compressed when written into the new mdbox mailbox.

Yes, I know, but I intend to do more than just convert to mdbox. I want
to fix the whole folder structure*, in a new filesystem with different
settings (turn on metadata-replication, and possibly also data
replication). So I need to free up some disks before this can start.

[*] move away from @Mails /atmail/a/b/abuser at domain folder structure to
mdbox:/srv/mailbackup/%256Hu/%d/%n, stop having home=inbox, 
possibly use many smaller fs's instead of one huge, move the indexes
inside home...


  -jf