[sclug] Load balancing

[n.a.haughton@bigfoot.com]

>
>
>
> ---------- Forwarded message ----------
> From: Alex Butcher <lug at assursys.co.uk>
> To: n.a.haughton at bigfoot.com
> Date: Tue, 5 Aug 2008 13:12:35 +0100 (BST)
> Subject: Re: [sclug] Linux as a web-farm load-balancer
> On Tue, 5 Aug 2008, n.a.haughton at bigfoot.com wrote:
>
>  I want to set up a load balancer in front of a pair of WinXP webservers,
>> to
>> test some software in a web farm environment. Cash is tight, so a Linux
>> solution sounds a good approach.  There are a couple of issues that I can
>> see might get in the way:
>>
>> 1. The WinXP webservers are in an Active Directory domain. Is this an
>> issue?
>>
>
> I can't think of any reason why it should be, providing that the AD domain
> controller can speak to the webservers directly and vice versa.
>
>  2. What exactly do I have to do to set this up? I have the latest
>> OpenSuse11
>> available, for example, but am prepared to try any distro that will
>> quickly
>> and easily solve my problem.
>>
>
> That depends on to what extent you need to keep track of which client is
> connecting to which real server. If all you're doing is serving static
> content, round-robin DNS would be sufficient (perhaps combined with a short
> TTL and some kind of availability test that can trigger removal of a failed
> machine from the DNS pool). If you need stateful tracking of web
> applications, I suspect you're out of luck without looking at things like
> F5's BIG-IP product range.
>
> I was having a look at Pound today, which puports to be a lightweight load
balancer that should just work, so it looks ideal. I got as far as adding an
Ubuntu 8.04 machine to the network and using a browser on that to
successfully access the webapp on either of the two WinXP webservers, so I
know that the Ubuntu machine can see the webservers. I then configured and
started Pound on the Ubuntu machine, and tried to send requests to that
from another desktop. What I expect should happen is that the requests
should be picked up by Pound and forwarded to one or other of the
webservers, and the response sent back to the client browser. What is
actually happening is - nothing. The client browser is sending the request
to the Ubuntu machine, but  no response is coming back.  I have set Pound to
listen on the IP address of the Ubuntu machine, port 80 - does anyone know
if this is what I am meant to do?


Neil