Lyle - CosmicPerl.com
perl at cosmicperl.com
Mon Oct 29 14:37:00 GMT 2007
Gareth Harper wrote:
> 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.
Single point of failure is something I'm really trying to avoid. How
reliable is a hardware load balancer? I guess it takes up 1u as well so
that's extra cost.
> 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.
I'm looking at two of supermicros twin inode in a 1U chassis. So
technically I'll have 4 hardware machines (in 2U), and maybe zen running
some more virtual machines.... With the problems I've had with my old
machine, I really want something that will stay up if one machine goes
down. The latest clients I'm targeting wont put up with downtime :(
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