Date: Sun, 16 May 1999 11:10:44 +1000 (EST) From: Andy Farkas <andyf@speednet.com.au> To: Graeme Tait <graeme@echidna.com> Cc: freebsd-isp@FreeBSD.ORG, info@boatbooks.com Subject: Re: Redundant servers Message-ID: <Pine.BSF.4.05.9905161110030.16018-100000@backup.zippynet.iol.net.au> In-Reply-To: <373DD794.15EF@echidna.com>
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How about: http://www.coyotepoint.com/freequalizer.shtml On Sat, 15 May 1999, Graeme Tait wrote: > I operate a colocated server (busy WWW, plus primary DNS and a small > amount of mail) for some clients, and we have been thinking about how to > assure (almost) uninterrupted service in the event of server failure. The > problem is that if physical access is required (e.g., because of hardware > failure), we may at times have difficulty achieving an acceptable repair > time. There is also the issue of minimizing downtime during major > upgrades. Since this machine takes online orders, downtime is directly > translatable into dollars of income lost. > > The existing machine is a plain PII-400 with 512MB RAM and 18GB total > non-RAID SCSI disk, and has been perfectly reliable to date. We could > purchase a fancy "server-grade" machine with RAID, redundant power > supplies, etc., but the fact is that there are still things that could > fail, and we'd still have to go down for certain upgrades. Also, such a > machine would be so expensive that having a spare would be out of the > question at present. > > For less total cost, we can commit a machine identical to the existing > server as a hot-standby, installed in the colo. So my first question is > does anyone have opinions on this or alternative strategies for > maximizing uptime, given that physical access to the server may be > severely restricted? > > > The second issue is how to actually run a hot standby, and effect a > switch on failure of the primary. > > I would want the spare machine on the network, since it could be used for > offloading some background tasks from the live machine, and also for > backing up some critical data. > > My thought was to assign the spare a separate primary IP address, and > have only that address active under normal circumstances. If it became > necessary to switch over from the live server, we would somehow take the > live server off the network (by software, remote power-down or physical > disconnection), and then run a script on the spare to ifconfig the 50 or > so IP alias addresses that the operational server answers to for DNS, > mail and WWW traffic. Maybe this could be automated based on monitoring > the primary machine. > > The other issue is how to make sure the spare machine is basically a > mirror of the primary machine. > > > -- > Graeme Tait - Echidna > -- :{ andyf@speednet.com.au Andy Farkas System Administrator Speed Internet Services http://www.speednet.com.au/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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