mouss wrote:
I am trying to "collect" methods to setup postfix in an HA
configuration, for "outbound" relay (no MUA involved). a use case is
using multiple postfix boxes to relay mail out for one or more exchange
servers. there are many possibilities. which one is
"good/recommended/easy/blahblah"? This is somewhat off topic since the
problem is mostly on the client (exchange or other) side rather than
postfix. but I think this is a real need. and if I get enough infos, I
can aggregate them and submit that as a howto/readme.
OpenBSD has a protocol called CARP (Common Address Redundancy Protocol)
that in a nutshell allows a virtual IP address to be shared among many
systems. It can do load balancing and fail-overs and is pretty easy to
work with from my experience. I've only used it in testing, so I can't
speak for how it stands up to real world scenarios. It was developed to
be an improvement over VRRP (previously mentioned in another email to
this thread) and because of licensing issues with VRRP. CARP appears to
be supported on FreeBSD and NetBSD also. There is a project for Linux
called uCARP that implements a user-space daemon of this protocol.
Here's some links for some more info:
http://www.openbsd.org/faq/faq6.html#CARP
http://www.freebsd.org/doc/en/books/handbook/carp.html
http://www.netbsd.org/docs/guide/en/chap-carp.html
http://www.ucarp.org/project/ucarp
http://www.countersiege.com/doc/pfsync-carp/
