Scalability and Elasticity

The world’s largest public cloud providers can accomplish a great deal through combining the wonders of server virtualization with the power that comes from owning vast data centers filled with racks upon racks of hardware resources. Elasticity and scalability are the two key principles through which a lot of this happens, and understanding exactly what they mean can help you optimize your design choices so you’ll get the most bang for your cloud buck.

Note that there really are no precise and authoritative definitions for scalability and elasticity in the context of cloud computing—and any definitions you do see are bound to involve at least some overlap. Nevertheless, building some kind of picture in your mind of how these two principles work can be valuable.

Scalability

A scalable service will automatically grow in capacity to seamlessly meet any changes in demand. A well-designed cloud-based operation will constantly monitor the health...