State-control-limit-based rejuvenation modelling and optimisation of the virtualised cloud server

Abstract

Software rejuvenation modelling and optimisation of the virtualised cloud server has been studied. A software rejuvenation policy on the virtual machines and the virtual machine monitor has been proposed in order to ensure high availability of the virtualised cloud server. The multi-component system, composed of the virtual machines and the virtual machine monitor, which are structurally dependent, has been reduced to the multiple two-component systems. The state-control-limit-based rejuvenation policy has been proposed and the joint probability density of the degraded state of the two-component VM-VMM has been derived. Furthermore, the solution to the joint probability density has been proposed. Finally, the stationary unavailability of the virtualised cloud server has been modelled. Numerical experiments have verified the correctness of the probability density function and the feasibility of the rejuvenation policy. The state-control-limit-based rejuvenation policy leads to lower unavailability of the virtualised cloud server in comparison with the lifetime-based rejuvenation policy.