Instance Types
EC2 uses Xen virtualization. Each virtual machine, called an "instance", functions as a virtual private server. Amazon sizes instances based on "Elastic Compute Units". The performance of otherwise identical virtual machines may vary.
As of December 2012, the following instance types are offered:
- On-demand: pay by hour without commitment
- Reserved: rent instances with one-time payment receiving discounts on the hourly charge
- Spot: bid-based service (runs the jobs only if the spot price is below the bid specified by bidder, the spot price is claimed to be supply-demand based however research refutes this claim )
Read more about this topic: Amazon Elastic Compute Cloud
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