Understanding Elasticity on the Cloud

The graph below illustrates the different approaches a cloud architects can take to scale their applications to meet the demand. Scale-up approach: not worrying about the scalable application architecture and investing heavily in larger and more powerful computers (vertical scaling) to accommodate the demand. This approach usually works to a point but could either cost a fortune or the demand could outgrow capacity.

The traditional scale-out approach: creating an architecture that scales horizontally and investing in infrastructure in small chunks. Most businesses and large-scale web applications follow this pattern by distributing their application components, federating their datasets, and employing a service-oriented design.

This approach is often more effective than a scale-up approach. However, this still requires predicting the demand at regular intervals and then deploying infrastructure in chunks to meet the demand. This often leads to excess capacity (“burning cash”) and constant manual monitoring (“burning human cycles”). Moreover, it usually does not work if the application is a victim of a viral fire.

Note: Both approaches have initial start-up costs and both approaches are reactive in nature.