At ZeroTurnaround, we need this for testing LiveRebel with larger deployments. LiveRebel is a tool to manage JEE production and QA deployments and online updates. It is crucial that we support large clusters of machines. Testing such environments is not an easy task but luckily in 2012 it is not about buying 800 machines but only provisioning them in the cloud for some limited time. In this article I will walk you through setting up a dynamic Tomcat cluster and running some simple tests on them. (Quick note: When I started writing this article, we had only tested this out with 100 Tomcat machines, but since then we grew to be able to support 800 instances with LiveRebel and the other tools).