Online Algorithm for Servers Consolidation in Cloud Data Centers

Makhlouf Hadji, Paul Labrogère (IRT SystemX)

Résumé

Servers consolidation (or Repacking) in clouds, consists to reassign services to physical servers, in order to efficiently reduce cost and improve infrastructure utilization. A smart placement of virtual resources is not enough to ensure system efficiency. This paper presents a novel and original online linear programming algorithm, based on b-matching theory, to optimally solve the consolidation problem with negligible SLA violations. To totally eliminate SLA violations, and to deal with dynamic workloads variations, we determine the optimal amount of a resource pool used to handle with over-used servers problem. We derive a solution whose performance is compared to a Best-Fit and a Bin-Packing formulation acting as benchmarks. Reported performance results show that the b-matching algorithm scale well and trade-off the number of migrations and servers to find optimal solutions. The b-matching uses fewer migrations but more servers to reduce SLA violations and resource pool utilization in the same time.