Purchase decision of cloud computing services under different instance utilization

Cloud computing or Infrastructure as a Service(IaaS) solutions such as Amazon's Elastic Computing Cloud(EC2) are very attractive for many commercial enterprises especially in today's limited or shrinking IT budgets environments. Cloud computing has been considered as a newest delivery model of enterprise's IT gradually. This paper is aimed at helping companies analyze several characteristics of multi-instance cloud services and provide a decision-making model of purchasing instances under different instance utilization. Using the concrete instances prices, a comparison is made of usage charges under different utilization of four instance purchasing-patterns of one-year period. Based on analysis presented herein, a decision-making table in purchasing one-year instances and the corresponding cost savings under different utilization is concluded.