Exercise about load balancing

Hi,
I would like to set up an exercise for my students concerning a kind of load balancing problem.
Suppose to have a web server with a web site created by using a CMS (joomla/drupal).
This CMS needs apache, php, a file system (of course) and MySql.
Put all those stuff in a VM and run it.

Suppose that a monitoring tool detects that you need a clone of the instance in order "slow down" the load. How can I set it up?

Observations:
- create a VM with apache+php+joomla+MySql should not be a problem
- monitor the cpu level and create a clone of the previous machine should not be a problem (by using snapshot)
- how I can split the HTTP requests in those two instances could be a problem (that is, I'm not sure how I can implement it)
- how I can manage the file system and MySql (since they must be perfectly synchronized) could be a problem (that is, I'm not sure how I can implement it)

How would you realize this kind of exercise? Which cloud computing platform (eucalytpus/openstack/nimbus) do you suggest?

Thanks,
Massimo