Elasticity vs Scalability

Written on 30^th April 2021

Elasticity and Scalability are two fundamental concepts when designing cloud native applications, however they can be difficult to define.

Fundamentally, the two concepts can be boiled down to the definitions.

Scalability is the ability of a system to accommodate larger loads. This can be achieved by either horizontally scaling out (adding more nodes) or vertically scaling up (larger hardware profiles).

Elasticity is the ability scale in (and scale out) infrastructure dynamically based upon current application loads. This can be a likened to an elastic band, whereby the elastic band can be stretched, and return back to its original size at any point, for any amount of time.

Elasticity is a crucial concept in cloud-native application designs, due to most cloud providers, such as AWS, operating upon a pay-per-use model. Elasticity can often provide a win-win situation, as it allows you to pay for resources you currently need, whilst maintaining the ability to ensure that you can meet rising demand when required.