[buug] hardware load balancing vs software

[Stefan Lasiewski]

--- johnd <john at jjdev.com> wrote:

> at my company we have a 'web-switch'
>
> for one example...traffic comes in and it balances bewteen two 
> apache servers
>
> each apache load balances across 4 tomcat servers...
> 
> Wouldn't it be better to just have the webswitch do all the load balancing?

What is the goal? Simplicity or speed? Removing the Apaches will certainly
simplify the network, but then you will lose the power of Apache and might
dump more processing on Tomcat, which might slow everything down.

Also, the webswitch will do the load balancing regardless if it's talking to
Apache or Tomcat, right?

In most networks, Apache really doesn't add much to the latency. The
load-balancing algorithm is pretty simple-- I think the module polls the
Tomcats once per minute or if there is a timeout.

> either by going straight to the tomcats (we proxy %100 of the traffic)

Plenty of people run their sites directly off tomcat, but I'm not sure if the
HTTP engine within Tomcat is intended to be an efficient HTTP server. Also,
are you sure you want Tomcat to handle the images and flat html files? It's
often more efficient to let Apache handle the static content and let Tomcat
deal with the dynamic JSPs.
 
> or if we need apache, to have 8 instances of apache..or a multiple of that
> running virtual hosts?
> 
> maybe two apache servers for redundancy each one running 4 virt hosts
> 
> basically what I'm curious about is if we have a hardware loadbalancer
> do we need to do more software loadbalancing?

If you have two or more Tomcats you would still need a way to evenly
distribute the requests, so software loadbalancing would still be necessary
between the Apache & Tomcat.


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