Dependability analysis and optimal maintenance problem for open source cloud computing

A cloud computing is attracting attention as a network service to share the computing resources such as networks, servers, storage, applications, and services. We focus on a cloud computing environment by using open source software such as OpenStack and Eucalyptus because of the unification management of data, low cost. In this paper, we propose a new approach to software dependability assessment based on a stochastic differential equation model in order to consider the interesting aspect of the numbers of components and users. Also, we analyze actual data to show numerical examples of software dependability assessment considering such characteristics of cloud computing environment. Moreover, we formulate a total expected software cost model for the environment of cloud computing. Then, we discuss the determination of optimum software maintenance times minimizing the total expected software cost.