Andy Mell wrote:
> I need to come up with a plan for making our email servers fully
>redundant...
>
>Theres always the approach of keeping a second machine on standby and
>copying the /var/spool and /var/mail across every ten minutes, locked with
>exim_lock of course. We use uw-imapd/pop3d and something similar would need
>to be done there too to prevent accesses to files.
>
A major PITA and not worth the effort IMHO
>The other option i was considering was one of the linux network mirroring
>filesystems, but this may be too much overhead and Im not sure how well it
>will do locking.
>
I used to have high hopes and love for GFS (GlobalFileSystem) long time
ago, but since it went commercial...
>Another option is to have a dual port raid system, but this isnt truly
>redundant because you have a SPOF in the raid system itself.
>
Use a SAN, with lots of internal redundancy and multiple paths to it.
The SAN we're using here never gave us trouble (one out of 3 redundant
power supplies wanted to be exchanged once in 3 years of service).
Half of all components in this setup could go down w/o crippling things,
with at most a short failover period.
As others mentioned, replicating the mail spool is an exercise in
pain probably futility. Make sure that the actual storage is as reliable
as possible and affordable and supply multiple, redundant front-ends to it.
Regards,
Christian Balzer
--
Christian Balzer Network Engineer Engineering
chibi@??? Global OnLine Japan/Exodus Communications K.K.
http://www.gol.com/
