Clustering in particular with ColdFusion and JRun can get fairly complicated pretty fast and I urge all who are going to embark on clustering to plan out how you want to cluster and why. Another key issue is to make sure when we are creating a web application that it designed and engineered from day one with clustering in mind. I have helped so many clients who hit major problems when they start building clusters, largely because the application was too tightly coupled to the environment it is running in. Hard-coded directory paths would be a classic example. In this blog posting I wanted to illustrate an interesting concept, well two in reality, Horizontal Clustering and Vertical Clustering. Let's look at a diagram....