The Impact of User Rationality in Federated Clouds

With cloud computing, the long-envisioned dream of computing as utility is achieved. Many of the current standalone cloud providers offer resources and services using pay-per-use fixed pricing. Spot pricing, recently introduced in Amazon EC2, is more efficient by setting the resource price dynamically, based on demand. However, this pricing scheme, similar to the uniform price auction, is truthful only when supply can be adjusted, such as the case of a standalone cloud provider. In a federated cloud, where resources from multiple cloud providers are integrated to increase elasticity and reliability, rational users can have a greater impact. In this paper, we evaluate the impact of rationality in a federated cloud, by comparing the consumer welfare achieved by spot pricing, currently used in Amazon EC2, and a strategy-proof pricing scheme. We consider different EC2 regions as providers in a federated cloud, and use traces of spot prices to determine the consumer requests and the user welfare. Our results show that spot pricing is not suitable in a federated cloud, where rational users can increase their welfare by being untruthful.