[Dovecot] mdbox - healthy rotation size vs default

[Michael Grimm]

On 26.08.2013, at 21:23, Charles Marcus <CMarcus at Media-Brokers.com> 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.
>> 
>> Not very helpful, I know,
> 
> 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'...


I must have missed that thread, sorry.

My observations are as follows:

1) if I delete mails in my mail client, mdbox files will not become reduced accordingly
2) if I do run something in my client like "remove all deleted mails from my account" (purged in client), mdbox files will not become reduced accordingly
3) if I do run "doveadm purge -A" on the server, mdbox files will become modified, see an example of a purge run a couple of minutes ago:

before (all my mail, ~800 mails purged in client):
-rw-------  1 vmail  dovecot  104856511 Aug 14 20:20 /var/mail/mike/storage/m.77
-rw-------  1 vmail  dovecot  104769054 Aug 25 03:14 /var/mail/mike/storage/m.89
-rw-------  1 vmail  dovecot  104848809 Aug 24 18:33 /var/mail/mike/storage/m.90
-rw-------  1 vmail  dovecot   24762837 Aug 26 21:26 /var/mail/mike/storage/m.91

after (all my mail, after "doveadm purge -A"):
-rw-------  1 vmail  dovecot  104856511 Aug 14 20:20 /var/mail/mike/storage/m.77
-rw-------  1 vmail  dovecot  104803218 Aug 26 21:26 /var/mail/mike/storage/m.92
-rw-------  1 vmail  dovecot  104802874 Aug 26 21:26 /var/mail/mike/storage/m.93
-rw-------  1 vmail  dovecot   21580496 Aug 26 21:26 /var/mail/mike/storage/m.94

Thus, from my point of view one needs to run "doveadm purge -A" on a regular basis *and* educate users to purge deleted mails in their clients on a regular basis as well.

(I hope I didn't misunderstand you right from the beginning.)

Regards,
Michael