Testing multi-node multi-layered web applications

I am testing (POC) different redundancy solutions for multi-node multilayered applications, ex: apache/php/mysql or any other framework.

I am aware of some tools like:

• MySQLTuner-perl for testing mysql backend
• Apache Benchmark / Jperf for web frontend

What I'am looking for is, a web app (could be simple web code) displaying some continuous db operations (reading/writing) in the web front-end, while I am shutting down nodes (backend or frontend) to simulate failures and proof that the service continue to work.

I appreciate some orientation, I am not a web developper, maybe I am expressing myself awkwardly.