How are Spot Instance, On-demand Instance, and Reserved Instance different from one another?
Both Spot Instance and On-demand Instance are models for pricing.
Spot Instance On-demand Instance
With Spot Instance, customers can purchase compute capacity with no upfront commitment at all. With On-demand Instance, users can launch instances at any time based on the demand.
Spot Instances are spare Amazon instances that you can bid for. On-demand Instances are suitable for high-availability needs of applications.
When the bidding price exceeds the spot price, the instance is automatically launched, and the spot price fluctuates based on supply and demand for instances. On-demand Instances are launched by users only with the pay-as-you-go model.
When the bidding price is less than the spot price, the instance is immediately taken away by Amazon. On-demand Instances will remain persistent without any automatic termination from Amazon.
Spot Instances are charged on an hourly basis. On-demand Instances are charged on a per-second basis
