AWS Elastic Cloud Computing

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What does Elastic mean in Elastic Cloud Computing?

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Refers to the ability of the system to adapt to workload changes by provisioning and de-provisioning resources in an autonomic manner. A good way to think about it is in the context of video streaming services such as Netflix. When a new or popular show comes up, demand goes up and so do compute needs. An elastic system has the ability to accommodate such changes in demand. Using an elastic system is not as cheap as running your own software but good for scaling up and down.

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What does elasticity mean in the context of an ec2 instance that's running genomics analysis?

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You can start an instance and stop an instance whenever you want it.

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What changes when demand or traffic increases?

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The number of instances that get added on or removed

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What the difference between elasticity and burstability?

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• Amazon EC2 allows you to choose between Fixed Performance Instances (e.g. M5, C5, and R5) and Burstable Performance Instances (e.g. T3). Burstable Performance Instances provide a baseline level of CPU performance with the ability to burst above the baseline.
  • T instances’ baseline performance and ability to burst are governed by CPU Credits. Each T instance receives CPU Credits continuously, the rate of which depends on the instance size. T instances accrue CPU Credits when they are idle, and use CPU credits when they are active. A CPU Credit provides the performance of a full CPU core for one minute.
  • For example, a t2.small instance receives credits continuously at a rate of 12 CPU Credits per hour. This capability provides baseline performance equivalent to 20% of a CPU core (20% x 60 mins = 12 mins). If the instance does not use the credits it receives, they are stored in its CPU Credit balance up to a maximum of 288 CPU Credits. When the t2.small instance needs to burst to more than 20% of a core, it draws from its CPU Credit balance to handle this surge automatically.
• Burstability is the property of an instance, elasticity applies to the use or disuse of additional instances.
• Burstable instances accumulate credits over time. These can be used when you need more compute.