Jeroen van Aart wrote:
> Hello,
>
> I was wondering if anyone can point me to information how to set up a
> backup email server. In such a way that if the main server is down one
> can switch to the backup with no to minimal loss of email (connectivity).
>
> I am thinking of a solution where if one server goes down (say an hd
> crash) the other server is used automatically. You could create a dns
> entry to randomly use one or the other IP, and mirror both systems. The
> central problem I believe is how to keep data like mailboxes in sync
> between 2 or more servers. If you'd use an NFS mounted server you create
> NFS related problems and an additional problem, of the NFS server
> possibly going down.
>
> (apologies for sending this mistakingly to a single person)
>
> Thank you,
> Jeroen
>
>
We're in the process of configuring something along these lines, though our Exim boxes are gateways to our Exchange
servers (apologies for swearing folks! ;) ) so we don't have mailboxes to replicate.
We intend to have two identical servers running openSUSE 10.2 with Heartbeat (
www.linux-ha.org) and DRBD (
www.drbd.org)
installed. DRBD will take care of the mirroring of data between the two systems via a second interface. This data will
be the MySQL database we use to translate "external" email addresses to "internal" Exchange addresses, and the entire
Exim installation (database, queue, config and logs).
Heartbeat will then be configured in Active/Passive mode so that upon failure of the "primary" server, the "failover"
server will mount its copy of the MySQL and Exim filesystems, configure its interface with the "cluster" IP address and
then start up MySQL and Exim. Though not quite instantaneous this can usually be done within about 15secs of a failure.
By mirroring the database, queue and config everything should carry on as if nothing had happened. Well, that's the
theory!
--
Paul Walsh
Information & Communication Technology,
UCE Birmingham, BIRMINGHAM B42 2SU, UK
