From owner-freebsd-questions@FreeBSD.ORG Sun Sep 26 19:28:53 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id AB08A16A4CE for ; Sun, 26 Sep 2004 19:28:53 +0000 (GMT) Received: from out006.verizon.net (out006pub.verizon.net [206.46.170.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4F07E43D1D for ; Sun, 26 Sep 2004 19:28:53 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from [192.168.1.3] ([68.160.246.51]) by out006.verizon.net (InterMail vM.5.01.06.06 201-253-122-130-106-20030910) with ESMTP id <20040926192852.EDEE22385.out006.verizon.net@[192.168.1.3]>; Sun, 26 Sep 2004 14:28:52 -0500 Message-ID: <4157185F.1000805@mac.com> Date: Sun, 26 Sep 2004 15:28:31 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Eric Crist References: <493F1EDF-0FE0-11D9-A586-000D9333E43C@secure-computing.net> In-Reply-To: <493F1EDF-0FE0-11D9-A586-000D9333E43C@secure-computing.net> X-Enigmail-Version: 0.86.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH at out006.verizon.net from [68.160.246.51] at Sun, 26 Sep 2004 14:28:52 -0500 cc: freebsd-questions@freebsd.org Subject: Re: Backup Mail Server Questions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Sep 2004 19:28:53 -0000 Eric Crist wrote: [ ... ] > One of my friends needs backup DNS/Mail in the even their connection > goes down. How do I go about setting it up so that his user base (about > 80 users) will not see any problems in mail transmission and reception > if their primary servers go offline. I would like mine to automatically > pickup the slack. Setting up redundant DNS is trivial: DNS is designed to do that. Setting up a backup MX is easy. It helps a lot if both mailservers are configured the same, and it is important that they have near-identical anti-spam and virus-filtering technologies. Setting up a truly redundant POP/IMAP reader box is extremely hard. To solve this problem for a local network, one normally uses a shared NAS box: in your case, this effectively requires one to set up a network-distributed filesystem, or some near-equivalent: for instance, a parallel database for mail stroage would serve as well. All sorts of nasty issues-- like the security of the data going between the two fileservers, or DBs, or whatever; significant added latency due to the storage mechanism confirming updates have propogated; etc appear. My opinion is that it's better to go with a primary mail reader box and make very certain that box doesn't go down by using redundant hardware and a backup network link is easier and less likely to suffer from the "lets create a complex system with lots of moving parts which never gets fully tested and thus breaks in some weird way when the unexpected happens" syndrome. :-) -- -Chuck