What types of instances does Amazon EC2 provide?
Amazon EC2 provides three types of instances – On Demand, Spot and Reserved Instances.
With On-Demand instances, you pay for computing capacity by per hour or per second depending on which instances you run. No longer-term commitments or upfront payments are needed. The compute capacity can be increased or decreased depending on the demands of the application.
Amazon EC2 Spot instances are spare compute capacity in the AWS cloud available to you at steep discounts compared to On-Demand prices. The drawback of these instances is that these instances can be withdrawn whenever EC2 needs it back. Hence, not suitable for the Production environment.
The only difference between On-Demand instances and Spot Instances is that Spot instances can be interrupted by EC2 with two minutes of notification when EC2 needs the capacity back. Reserved Instances provide you with a significant discount (up to 75%) compared to On-Demand instance pricing. Reserved instances are recommended for scenarios where the usage is predictable and steady. For nurses the load and usage of the application can be predicted. Also, it is expected that this not experiences any sudden spikes regarding demand and usage. Therefore, Reserved instances are definitely the most suitable and economical options for nurses. Amazon RDS also provides On-Demand instance and pay for what you use the feature.