dovecot - Aug 2010 - Live Mirror dovecot / OS X 10.6.4

I want to set up mirrored postfix/dovecot servers using two mac mini servers
(OSX 10.6.4)  located in different locations (Canada and the US to be specific)
for redundancy.
The idea is to have one as the primary MX ("mail.corp.com") and the
other as the secondary ("webmail.corp.com"). If the primary goes down
clients would revert to webmail until the primary is back up.

The plan is to use rsync for this. My challenge, however, is what all I need to
rsync to have a "live" backup. Rsync for backup isn't an issue,
but I will need to rsync users (system and virtual).

Anyone have experience with this? So far it seems that apple puts things in lots
of non-standard locations. I suppose I could to a blanket rsync on /var, but
that seems a bit much.

Thanks in advance.

On Tue, 2010-08-24 at 12:27 -0400, Eric Boltz (MMI/UPC)
wrote:
> The idea is to have one as the primary MX ("mail.corp.com") and
the other as the secondary ("webmail.corp.com"). If the primary goes
down clients would revert to webmail until the primary is back up.
> 
> The plan is to use rsync for this. My challenge, however, is what all I
need to rsync to have a "live" backup. Rsync for backup isn't an
issue, but I will need to rsync users (system and virtual).
Two potential problems I see with this:

1. If users can do any changes on the secondary server (flag changes,
saving new mails, etc), you're going to have problems syncing the
changes back (without losing any changes or causing other problems).

2. If users can access the secondary server via IMAP clients, the
clients could become confused if the secondary server isn't completely
up-to-date.

With v2.0 dsync would help with the first problem.