Cloud Application Architectures

Chapter 7. Scaling a Cloud Infrastructure

One of the most useful features of cloud infrastructures is the ability to automatically scale an infrastructure vertically and horizontally with little or no impact to the applications running in that infrastructure. In truth, useful is an understatement. This feature fundamentally alters IT managers’ relationships to their infrastructures and changes the way finance managers look at IT funding. But the feature is a double-edged sword.

The obvious benefit of cloud scaling is that you pay only for the resources you use. The noncloud approach is to buy infrastructure for peak capacity, waste resources, and pray your capacity planning was spot on. The downside of cloud scaling, however, is that it can become a crutch that lazy system architects use to avoid capacity planning. In addition, over-reliance on cloud scaling can lead an organization to respond to demand—and thus add cloud instances—when the demand in question simply has no business benefit.

In this chapter, I guide you through the issues of scaling a cloud infrastructure so that you can intelligently apply the full capabilities of the cloud to your IT infrastructure without falling prey to its dangers. Your success will start with reasonable capacity planning.