[Dovecot] mdbox - healthy rotation size vs default

[Jan-Frode Myklebust]

On Mon, Aug 26, 2013 at 03:31:20PM -0400, Charles Marcus wrote:
> >On 2013-08-26 2:58 PM, Michael Grimm <trashcan at odo.in-berlin.de> wrote:
> >>As a very rough estimate I do estimate a 5% waste of space
> >>regarding deleted messages. But, my handful users are very
> >>disciplined in purging their deleted messages on a regular basis
> >>(I told them to do), and thus my regular "doveadm purge -A" runs
> >>will reduce that amount of wasted disk space to a minimum.
> >
> >Are you sure about that? There was a thread a while back (I
> >recently posted a response to it) about this, and it sounded like
> >the mdbox files would *never* be 'compacted' (reduced in size from
> >deleted messages)... my reply was on 8/23, thread titled "Dovecot
> >never release preallocated space in mdbox'...
> 
> Ooops, sorry, it was about *automatically* compacting them... I think...
> 

And Timo seemed to reply that hole punching was something doveadm
purge could conceivably do, but doesn't do at the moment. Timo, could
you please clearify a bit here?

Does non-preallocated (mdbox_preallocate_space=no) m-files get hole
punched (or space re-used for new messages) after running doveadm
purge? Or can we end up with a huge $mdbox_rotate_size size m-file,
with only a single small message remaining after all other
messages has been purged?


  -jf