[Dovecot] Users with large (4GB) inboxes crippling dovecot

[Scott Silva]

on 5-28-2009 12:24 PM Scott Haneda spake the following:
> On May 28, 2009, at 10:39 AM, Scott Silva wrote:
> 
>> on 5-28-2009 9:36 AM Timo Sirainen spake the following:
>>> On Thu, 2009-05-28 at 02:07 -0700, robforrest wrote:
>>>> What is happening is that as users log in (via thunderbird), they
>>>> are shown
>>>> the contents of their mailboxes.  However, when they try and access
>>>> a given
>>>> email, they get no response even if they wait upwards of 10 minutes.  I
>>>> believe that the problem has arisen from their huge inboxes, several
>>>> users
>>>> have inboxes in excess of 4GB.
>>>
>>> mbox_very_dirty_syncs = yes would probably make these mailboxes usable
>>> without having to split anything or convert to Maildir. That requires
>>> Dovecot v1.0+ of course.
>>>
>> The indexing improvements in 1.0 would probably help a lot also. I have
>> several large mboxes and also some gzipped log storage boxes and 1.1
>> is fairly
>> speedy with them. A full re-index in thunderbird takes right at a
>> minute with
>> a 6gb gzipped box I just tested.
> 
> 
> Can you state what the size of your "several large mboxes" is?  I have
> been curious about this.  My current email server forces me to manage my
> IMAP boxes not based on size, though I believe there is a less than 2GB
> limit, but on message count.  Too many messages kills me, the storage is
> one file for each mailbox.
> 
> As I am migrating to Dovecot, it would be nice to know what I am in for,
> and if I can simply stop managing this?  My users are going to use the
> server like it is gmail, and never file a darn thing.
> 
> One thing I wanted to do, was look at the inbox, and if it is over
> xMB's, rename it to inbox.date which will force the user to deal with
> it.  However, if there is no need to do this, and Dovecot can handle it,
> then I would prefer to skip the intrusion on my users.
> 
> What happens in Dovecot if one inbox is massive and in fact hurting
> performance.  Does that performance hit trickle down to all users, or
> just that one user?
> 
> Thank you, and looking forward to being 100% Doevcot here in a few weeks.
My largest is about 5+ GB gzipped (I thought it was 6gb until I just checked),
but I am on a 64 bit server and don't have a 2 gb filesize limit. I have
several users with 2 to 3 GB inboxes on IMAP, and don't get any complaints. I
have been considering going to maildir, and scripting some stuff like moving
messages older than 30 days out of the inbox, and also purging any messages
marked as deleted, and also older stuff in the trash. Maildir is much easier
with this since it is one file per message instead of one file per folder.

If one user does manage to really hose a box, the re-indexing that dovecot can
slow the system for a little while, but it clears up pretty fast. Only rarely
have I had to intervene and kill a process.

The one place where dovecot might be less than stellar is with pop3 access
from outlook if they leave mail on the server. It can get confused sometimes
and re-download everything, but this is Outlook's problem, not dovecot's.

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