On Wed, 2008-03-26 at 14:37 -0700, Jeroen van Aart wrote:
> Or is there a way to access a server directly, automatically, when a 
> load balancer fails? Maybe I am missing some obvious things.

You are :)

If you're using Linux boxes, and you have only two - forgetting for a
moment the obvious issue of a shared mailstore - then they can act
simultaneously as:

 = load balancers
 = high availability servers
 = MTA, MSA
 = IMAP / POP / Web servers

Using LVS - http://www.linuxvirtualserver.org/ - which is built in to
the Linux kernel.

Heartbeat gives you the HA part
Heartbeat can trigger ldirectord, the linux-ha project's load balancing
manager
Exim does the MTA, MSA part
You choose what to do the rest with :)

The difficulty with a two box solution is the last part - how to achieve
a shared mailbox store. Oh, hang on, it's not *that* hard if you use
something like DRBD - http://www.drbd.org/ - which Heartbeat can also
manage...

So, with a pair of boxes and a reasonably recent version of Linux (I
choose RHEL based distros from personal preference and familiarity, but
that's a religious fight I'd rather see raised here!) you've got it all.
No need for a third box, no SPOF in sight.

Be ready, however, for a learning curve...

Graeme


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