Autoscaling

Autoscaling, also spelled auto scaling or auto-scaling, and sometimes also called automatic scaling, is a method used in cloud computing that dynamically adjusts the amount of computational resources in a server farm - typically measured by the number of active servers - automatically based on the load on the farm.

Since such metrics may change dramatically throughout the course of the day, and servers are a limited resource that cost money to run even while idle, there is often an incentive to run "just enough" servers to support the current load while still being able to support sudden and large spikes in activity.

[20] On-demand video provider Netflix documented their use of autoscaling with Amazon Web Services to meet their highly variable consumer needs.

[23] On June 27, 2013, Microsoft announced that it was adding autoscaling support to its Windows Azure cloud computing platform.

[10][27] Oracle Cloud Platform allows server instances to automatically scale a cluster in or out by defining an auto-scaling rule.

[9] In a blog post in August 2014, a Facebook engineer disclosed that the company had started using autoscaling to bring down its energy costs.

Scheduled scaling is useful, for instance, if there is a known traffic load increase or decrease at specific times of the day, but the change is too sudden for reactive approach based autoscaling to respond fast enough.

For parts of their infrastructure and specific workloads, Netflix found that Scryer, their predictive analytics engine, gave better results than Amazon's reactive autoscaling approach.