replication

[Bron Gondwana]

On Fri, Nov 12, 2010 at 02:02:01PM -0500, Ron Vachiyer wrote:
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> Hello,
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> I am currently investigating the possibility of adding a second cyrus server, the goal being to entirely duplicate the mailspool/userbase and have users POP in some sort of balanced means, either DNS load balancing or otherwise.  We have a pool of inbound MX servers that handle email, delivering to Cyrus over lmtp.  In the event of a crash, we would want to repair/rebuild the dead server and have it re-join the pairing.
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> I have read on this list's archives that having user interaction on two replicated servers is iffy, and I wonder what the point is, or is there alternative documentation/methods I should be considering to do this.  If it is true that popping email off of two servers set up in replication is a bad idea, I wonder what the point of it really is?

It's getting better, but it's still not 100% reliable to have
master/master replication between two servers with interactions
going to both sides.

It SHOULD be safe now to have a single master/master setup with
individual users on one side or the other - but note that nobody
is known to be running that setup successfully yet.

As for what the point is?  I don't know about you, but I run a
24hr/day shop, and I like to be able to take a server down for
maintainence in about 2 minutes, with users seeing a brief
disconnection and then being able to keep using the service
with minimal disruption.

Bron.