Energy-efficient planning of QoS-constrained virtual-cluster embedding in data centres

It is crucial for cloud service providers to fulfil their tenants targeted quality of service (QoS) requirements, yet, providing such QoS in an energy efficient manner is of paramount importance to optimizing operational costs. In this paper, we study the energy efficiency of virtual cluster embedding in data centers. More specifically, we focus on designing fast algorithms to place in an energy efficient manner virtual clusters, including virtual machines, virtual switches and virtual topology with bandwidth requirements. We first model the problem as an integer programming problem, and prove its NP hardness, then based on a relaxed version of this model, we propose an approximate algorithm to solve it efficiently.