building site with 250 concurrent users in php

[surreddy]

Hi,

We have a website that is using Joomla (joomla.org)
content management system. We need this website to support upto 250 concurrent users during the peak
time.

The current problem with our solution is that it is going down when the
concurrent users number is breaching 50. By increasing the RAM on the web
server to 512MB we were able to handle this problem to some extent. However,
we are not very sure that increasing the RAM in proportion to the users
number might not be a good idea. We think that going for an application
server might help us in managing the concurrent users and server resources
issue in a much better way.

What do you feel about this thinking? We really
appreciate your detailed response and an appropriate solution
recommendation.

Many Thanks for your help!
Surreddy

[etully]

We just spent $50,000 to address this exact same problem. We bought two machines to serve as load balancers, four web servers, and two machines to serve as a storage area network. Take a look at: http://www.linux-ha.org/

The system relies on two main pieces of software: ldirectord and heartbeat.

One load balancer is running while the other is shut off. Heartbeat is running on each load balancer machine. If Heartbeat sees that the load balancer on the other machine is not functioning, it starts up the local load balancer. This way, you only have one load balancer running at a time... but you have a backup ready to jump in if the other one goes down.

Now that you have redundant load balancers, you can put in as many web servers as you want. Two, ten, fifty, whatever. The load balancer software (ldirectord) checks the web servers to see which is busy and routes traffic to the less busy servers.

The beauty of this system is that when you need to add another web server, you just do. You don't need to change anything on your web site or anything.