[Dovecot] cluster with dsync mirror

[Bryan Vyhmeister]

On Mon, Aug 16, 2010 at 5:15 AM, Timo Sirainen <tss at iki.fi> wrote:
> On 16.8.2010, at 7.33, Bryan Vyhmeister wrote:
>
>> Would it work to run 'dsync mirror' every minute against either mdbox
>> or sdbox mailbox on a dedicated network connection between two (or
>> potentially three or four) mail servers? I'm trying to avoid using a
>> NAS/SAN or some other dedicated NFS server in a simple environment
>> with a limited number of users. Everything else about the systems
>> could be identical. Both could receive mail using Postfix with dovecot
>> LDA. Thank you.
>
> Were you thinking about master/slave or multi-master setup? Multi-master might work ok with director, as long as dsyncing is done often enough.

I was thinking about multi-master. I didn't think about director but
that would solve the issue of not connecting to the same server each
time and would cause dsync to not have to happen quite as often.

>
> If you don't have many users, then maybe dsyncing once a minute is enough. A more optimal version would go something like:
>
>  - create a dsyncing server process
>  - create a Dovecot plugin (using notify plugin, similar to mail_log) that notifies dsyncing process every time some user's mailbox changes
>  - based on that information, dsyncing process either runs dsync or delays it a bit. like maybe flag changes and expunges would be delayed a bit, but new mails would be immediately synced
>  - run a full dsync for every user once in a while anyway, just in case some notifications were missed
>  - implement a QRESYNC-like syncing for dsync to improve performance and reduce network traffic

I'll have to investigate this further. This sounds like an even better
solution. Thank you!

Bryan