Reliability evaluation for cloud computing system considering common cause failure

Virtualization has been used in cloud computing to build multiple Virtual Machines (VMs) on a single physical machine, which enables computing resources partition and improving the physical resources utilization efficiency. However, the use of virtualization brings new challenge in reliability modeling for cloud computing. For example, when server failure occurs, all VMs co-located on the server cannot be operated, which is a typical common cause failure (CCFs). Since the task is executed by VMs, the states of VMs decide whether cloud computing can accomplish the given task. This paper proposes a new reliability model for cloud computing considering both server failures and VMs failures. Both fault tree and state-space models are used to solve this problem, and to reduce the computational complexity, a simplified method is provided to reduce the number of states.