[Linux-cluster] Trying to locate the bottleneck

[Raymond Setchfield]

Hi

I am trying to find a problem here with a setup which I am currently 
testing.

This is the current setup which I have at the moment

15 web farm servers which are running vhost-ldap module and also have 
ldap caching enabled. Which are behind 2 Load balancer servers which are 
in fail over. The software which it is currently running is Piranha on 
the load balancers.

I am using siege to get some benchmarking done on these to test 
basically their availability when pushing high concurrency.

At 100 (99.60 according to siege) Concurrent Connection it appears to be 
all ok with 99.89%. At 120 (119.52 according to siege) Concurrent 
connections I get 99.9%, and at 130 (129.51 according to siege) 
Concurrent Connections I get 100% availability.

However pushing it any further than this, for example 150 concurrent 
connections it is falling over and siege bails out with multiple 
connection time outs. I am trying to find the bottle neck here and I am 
wondering if it is software which I am using for the load balancers or a 
limitation with apache.

The command I am using for siege is pretty simple nothing special;

siege --concurrent=150 --internet --file=urls.txt --benchmark --time=60M

My lvs.cf file can be found here to show you guys the config which I am 
using.

http://pastebin.com/m52d6cc23

Any help would be greatly appreciated

Many Thanks

R.