Cyrus IMAP and MySQL mailboxes (Building load-balancing cluster)

[Bron Gondwana]

On Fri, Nov 17, 2006 at 11:54:39AM +1000, Sarah Walters wrote:
> Why don't you look at throwing two beefy boxes at this problem in a
> hot-spare
> configuration? Have a single large box managing the mail and a heartbeat
> so
> that if one goes down the other immediately takes over its IP and just
> keeps
> going? You will lose anything that is actually in memory, but that
> shouldn't
> be an issue as long as you are using a SAN and immediately committing to
> disk
> rather than using a solution like MySQL. There is no need for load
> balancing
> here as far as I can tell, and what you lose in having to buy a chunkier
> server
> you will gain in reduced power consumption and associated data centre
> costs.

That doesn't scale forever unfortunately, though you can get pretty
beefy, eventually you need to scale sideways.  Once you're scaling to
multiple machines you need a proxying frontend of some sort (murder or
our perdition/nginx solution, take your pick) and this all becomes a lot
easier.

Also it means you don't have hot spare hardware (or cold spare hardware)
sitting in your datacentre doing nothing if you're willing to take the
time to make multiple cyrus instances work on the same machine.  Then
you can have both masters and replicas on the same host, and just switch
one up to be a master when the other dies.

Bron.