Date: Wed, 16 Sep 2009 09:15:32 -0700 From: "Michael K. Smith - Adhost" <mksmith@adhost.com> To: "Steve Bertrand" <steve@ibctech.ca>, "Matthew Seaman" <m.seaman@infracaninophile.co.uk> Cc: questions@freebsd.org Subject: RE: New mail server setup Message-ID: <17838240D9A5544AAA5FF95F8D52031606AFCA07@ad-exh01.adhost.lan> In-Reply-To: <4AB0F17B.1030400@ibctech.ca> References: <4AB0584D.3050206@eagle.ca><4AB0844B.5080804@infracaninophile.co.uk><4AB0E97B.4060606@ibctech.ca><4AB0ECE8.2080905@infracaninophile.co.uk> <4AB0F17B.1030400@ibctech.ca>
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> -----Original Message----- > From: owner-freebsd-questions@freebsd.org [mailto:owner-freebsd- > questions@freebsd.org] On Behalf Of Steve Bertrand > Sent: Wednesday, September 16, 2009 7:09 AM > To: Matthew Seaman > Cc: questions@freebsd.org > Subject: Re: New mail server setup >=20 > Matthew Seaman wrote: > > Steve Bertrand wrote: > > >=20 > >> If anyone has a setup that has redundancy for their IMAP/POP > services, > >> and a method to keep the changing data relatively up-to-date, I'd > love > >> to hear about it. > > > > Now, that is a different kettle of fish. This is a job for cyrus > imap. > > I suggest googling for 'cyrus murder' -- this is almost, but not > quite, > > a fully resilient mail store / IMAP system. Your mail store is > divided > > into frontend IMAP protocol servers which handle user auth etc. and > back-end > > mail stores. The protocol layer servers are fully resilient and you > can > > fail over a user session at will, but the mailstores don't quite get > there: > > mail is replicated across different stores, but actions modifying the > mail > > store are not transactional across all the mail stores. Or in other > words, > > you can lose a small amount of data if one of the mail stores goes > bang at > > precisely the wrong moment. Even so, it will do better at keeping > multiple > > copies of a mailstore in synch than any locally scripted rsync setup. >=20 > This is *EXACTLY* what I was looking for! >=20 > The possibility of loosing an extremely small amount of data far > outweighs the possibility of a multi-hour outage where 3,000 users are > receiving "can't reach the POP3 server" errors. >=20 > Besides, our incoming SMTP gateway boxes cache all incoming email for > 24 > hours, and we can re-deliver any message to the back-end we wish during > that window. >=20 > I really try my best to design/implement all the systems I can like our > networks... multiple paths and extremely quick convergence. Being able > to take a box down to test/perform an upgrade, or during a failure > without client impact is well worth any initial large learning curve > imho. >=20 > Thanks, >=20 > Steve Hello Steve: Another approach would be a cluster of Postfix servers and Dovecot servers behind PF load balancers. We have 3 "POP" servers (IMAP/POP), 9 Mail Servers, 2 Defer servers and 5 Filter servers that process over 20 million messages a day without a blip. We can take individual servers out of the pool for maintenance, etc. Everything is fed to a set of redundant NAS for the data storage and common configuration files. Regards, Mike -- Michael K. Smith - CISSP, GISP Chief Technical Officer - Adhost Internet LLC mksmith@adhost.com w: +1 (206) 404-9500 f: +1 (206) 404-9050 PGP: B49A DDF5 8611 27F3 08B9 84BB E61E 38C0 (Key ID: 0x9A96777D)
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