[Dovecot] PostgreSQL driver supporting [round-robin] load balancing and redundancy [LONG]

[Marshal Newrock]

On Wed, 14 Apr 2010 20:56:13 +0200
Rainer Weikusat <rweikusat at mssgmbh.com> wrote:

> One of the things my employer uses dovecot for is as mail download
> server for an 'e-mail purification service' (AV/ anti-spam) for
> smartphones. The service itself presently runs on a rented server
> somewhere in the UK and the corresponding 'web service' front-end and
> user account/ mail account database resides on a server in
> Germany. The UK dovecot server uses the PostgreSQL server on the
> German machine for user authentication. The latter is reachable using
> two entirely different 'internet paths' and there was an outage of
> several hours on one of them a couple of weeks ago. This prompted
> some frantic network reconfiguration efforts in order to get the
> abovementioned service going again and resulted in the conviction
> that - ideally - the dovecot server should be capable of using
> connections to multiple PostgreSQL servers (or a single server
> reachable via several IPs) simultaneoulsy, distributing requests
> among them, and should be capable of detecting a possible problem on
> one of the db server connections and use the still functioning ones
> to continue operations.

Have you looked at anything like pgpool?  I looked at this a while
back, and from what I could see, it sits between the client app and
postgresql, and works fairly invisibly.  It does appear to have a
failover mode which will do what you want.  I haven't yet implemented
pgpool anywhere, so I can't give details or opinions.

-- 
Marshal Newrock
Zordio, LLC - http://www.zordio.com
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