Reliable Approach to Sell the Spare Capacity in the Cloud

Traditionally, Infrastructure as a Service (IaaS) providers deliver their services as Reserved or On-Demand instances. Spot Instances (SIs) is a complementary service that allows customers to bid on the free capacity in the provider data centers. Therefore, the decrease in the free capacity may result in terminating instances abruptly. To ensure fair trading, the provider does not charge customers for the interrupted partial hours. However, our experiments show that uncharged time could rise up to 30% of the instance total run time, which means a reduction in the provider's profit. In this paper, we propose an Elastic Spot Instances (ESIs) approach, where instead of abruptly terminating the SI, the provider scales down their capacity proportionally to the increase in the price. Our approach delegates the task of interrupting the instances into the customers, but at the same time keeps the control in the provider side to isolate SIs' impact on the other services. We validate our approach along different periods of SIs history traces.