In this interview with Catalyst's Director, Mike O'Connor sheds light on how enterprise scaling of Lamp and use of CMS including DRUPAL and MOODLE can dramatically benefit companies.

"The back-end database servers will run either MySQL or PostgreSQL, depending on the individual project's requirements. In addition, the back-end tier may also provide additional services like Memcached or Apache Solr.

Finally, in some situations we may deploy a caching tier in front of the application servers. Originally we would use Squid for this caching tier, however for recent deployments we have used Varnish instead, as we find it is far more flexible."