Date: Thu, 8 Apr 2010 16:01:30 +0200 From: Robert Joosten <robert@ml.erje.net> To: freebsd-stable@freebsd.org Subject: Re: fault tolerant web servers on freebsd Message-ID: <20100408140130.GC1555@ismet.erje.net> In-Reply-To: <4BBA51B9.6010803@gausus.net> References: <1209800810.33861270466947931.JavaMail.root@dagobah.intersec.pl> <4BBA05A2.40706@intertainservices.com> <4BBA1823.1090305@gausus.net> <4BBA4334.1020506@interazioni.it> <4BBA4478.7030302@gausus.net> <20100405164306.hmy4n8pvs4goc8ks@www.goldsword.com> <4BBA51B9.6010803@gausus.net>
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Hi, > Let's say i need to run a few php/sql based web sites and I would like > to maintain uptime of about 99,99% per month. > From what You say I need some level of HA system, to maintain the > required uptime. Okay > (i'm skiping (..) network issues at the moment). Then you won't succeed. Four nines availabillity without regarding network outages... sjeesh. > Few people have told me about a setup with linux, drbd and heartbeat > which offers them some level of HA. Has anyone tried anything similar on > FreeBSD? Did you actually *look* around for possible solutions ? I mean, I searched with google and found geom + ggated solutions... Go figure. Depending on your budget, I would build two 'systems', spread over two coloc's. Use two squid/memcached caches, two backend servers with http-daemons and php on it, two sql servers that replicate in realtime, all (maybe exclude the sql servers from that.. depending on writes figures) connected to a NAS. Having caches at the frontend, make sure you fully understand http://www.mnot.net/cache_docs/ (for example, may more resources are available). Then, have that NAS replicate to the other coloc site (don't forget the encryption heh). Pay attention to the switched LAN behind it. Maybe redundant switches would be a very clever investment. At last, have 2 dns A/AAAA pointers to both sites with a reasonable but short TTL that you can change right away. These autoritive dns servers must be as redundant as well. Now we're talking about resiliency. And money, so skip out all what proves to be too expensive. I'm sure you already estimated how many dollars unavailabillity costs you, so invest wisely. If this is a commercial hosting exercise, buy stuff for the upcoming 36 months. After that, redesign may be wise. You wanna learn how other folks are doing this ? Have a look at wikipedia ! And also try to learn from their power outage few weeks ago :-/ You may poke around at http://wikitech.wikimedia.org/view/Main_Page and get some idea's. Goodluck. Robert
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