Tim Jackson wrote:
> matt@??? wrote:
>
>> I am currently trying to setup multiple mail servers so should the smtp
>> server go down, we will receive mail to our of our other smtp servers,
>> then when the original server comes back, the mail is passed on there.
>
> [... replication of mailstore using unison ...]
>
>> Can anyone see any potential problems with this method..... or do you
>> think it will work fine?
>
> I would think you would be better off replicating the maildirs using
> DRBD (www.drbd.org) between the two machines; it will provide more
> "seamless" failover, as well as up-to-the-second replication.
>
This is indeed a good solution, but unfortunately, it only works if you
are using linux.
The problems using unison are however somewhat important:
1: It's is not synchronous replication (that means you can lose mails if
the "main" server crashes and sync isn't done yet)
2: Unison needs to fstat() all files when looking for updates, this can
take some time, and is using quite a bit of disk I/O. But your
filesystem cache may help in this case. There are also some
optimizations that can be done in the config to help mitigate this point.
