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From: Jan Grant <jan.grant@bristol.ac.uk>
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Cc: Liste FreeBSD <freebsd-questions@freebsd.org>
Subject: Re: Cluster mail system using FreeBSD 
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On Wed, 23 Aug 2006, bsd wrote:

> The idea is to offer a simple and very efficient solution in order for the
> server to have a 100% uptime under any circumstances.

That goal is not realistic.

> I was first thinking about using Linux-HA aka. "heartbeat" and syncing 
> the two boxes using rsync ?

One question is whether your uptime definition means "someone can 
connect via IMAP" or "someone can connect via IMAP and IMAP 
acknowledgements of state-changing operations are guaranteed to be 
replicated across the cluster". If you actually want your cluster's 
semantics to preserve email client operations in the face of the loss of 
one member of the cluster then rsync is not enough.

> What other solution would you think of ?

You might want to chase down the Cambridge patches to cyrus, which added 
an application-level transaction log to that particular imap server.

-- 
jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/
Tel +44 (0)117 3317661   http://ioctl.org/jan/
Leverage that synergy! Ooh yeah, looking good! Now stretch - and relax.