The difference between cloud elasticity and scalability – and why both matter

October 31, 2014

When it comes to the adoption of cloud computing in the enterprise, CIOs and other decision makers must evaluate potential cloud solutions on a number of criteria. Things like cost, performance, security and reliability come up often as key points of interest to IT departments. Joining those criteria at the top of the list of importance are the concepts of scalability and elasticity.

We often hear about scalability and elasticity in tandem with one another. Sometimes the terms are even used interchangeably. While these two words are closely related in the world of cloud computing, they are not actually the same thing.

Scalability vs. elasticity
On the surface, looking at these concepts as two separate functions seems like splitting hairs, but the difference between the two must be noted and taken into account by decision makers who want to understand their cloud options as deeply as possible before committing to any one.

According to TechTarget, scalability is the ability on the part of software or hardware to continue to function at a high level of performance as workflow volume increases. In addition to functioning well, the scaled up application should be able to take full advantage of the resources that its new environment offers. For example, if an application is scaled from a smaller operating system to a larger one should be able to handle a larger workload and offer better performance as the resources become available.

Scalability usually refers to adding resources and performance. As TechTarget pointed out, elasticity generally means the opposite – scaling down capacity or resources as they are no longer needed.

Where the two concepts converge
We know that elasticity and scalability are different, but there is a common theme between the two: adaptability.

A cloud service that is both scalable and elastic is an adaptable solution. An adaptable cloud environment is one that allows the IT department to expand or contract capacity as needed in response to an ever changing business environment.

ZDNet reported that managers need to weigh adaptability heavily when deciding and negotiating for a cloud solution. Internal and external conditions change so rapidly today that a company may need to add or decommission cloud capacity on short notice. A cloud solution may be a home run on things like reliability, security and performance, but if it lacks adaptability, decision makers may want to turn elsewhere.