gareth at migcan.com
Mon Oct 29 13:51:59 GMT 2007
Lyle - CosmicPerl.com wrote:
> On a side note, while we are on the subject... I plan on co-locating 2
> servers with 49pence. I want it setup so that one if a mirror of the
> other, and if one falls over it automatically goes to the other. I'll
> be running Fedora, but not having done this before I've no idea how to
> get this setup, or even what this kind of setup is called. If someone
> would care to enlighten me it would be much appreciated :)
The best way to run that is generally with an active-active system.
Both systems take traffic and you load balance between them. If one
machine goes down your load balancer notices and stops sending traffic
to the mahcine which is down. The advantage of this is you don't end up
having duplicated hardware sat there doing nothing, and you also get the
confidence that your "backup" machine is actually working since it's
dealing with live traffic all the time anyway.
You can either get a dedicated hardware load balancer, or use something
like mod_proxy under apache which now has a mod_proxy_balancer plugin
for exactly this kind of thing.
Obviously the slight downside to this is you need a third machine to act
as a load balancer (again, ideally 2 with a manual failover process if
the balancer goes down) but I guess you would need the same even with an
automatic failover process as you will need something which chooses to
direct the traffic to one machine or another.
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