--On 13 August 2009 20:49:07 +0100 Mike Cardwell <[email protected]> wrote:
> pch0317 wrote: > >> Is exim capable to work in high-availability or load-balancing cluster? > > Yes. > >> If yes, where I can read about this. Please, give me a hint. > > 1.) Install Exim on each node in cluster > 2.) Done. > > Any sort of clustering or load balancing would be done outside of Exim. > high-availability is "built in" to SMTP by the ability to set multiple > MX records, and the ability to retry. > Which is fine for MX servers. Not so good for MSA. MUAs (user clients) don't use MX records, and don't retry even if the smtp server address is a round robin in the DNS. At least, none of the servers that I've tried. We have a cluster of four OSX Server servers with Exim. With three, Apple's IP failover was just about managable. With four we switched to using Wackamole on Spread. That works quite nicely, but occasionally a failover throws up faults with ARP caches, leaving some of the IP addresses unavailable. As a result, we've recently put the MSA servers behind a CoyotePoint equaliser. We publish a single IP address for MSA, and the equaliser does load balancing and high availability. It regularly checks to see that it can get an SMTP greeting from each of the servers - if not, then that server doesn't get any traffic till its fixed. Of course, the equaliser becomes a single point of failure... And so it goes... The equaliser doesn't fail as often as the ARP cache corruptions occur. -- Ian Eiloart IT Services, University of Sussex 01273-873148 x3148 For new support requests, see http://www.sussex.ac.uk/its/help/ -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
