Virtual machine consolidation in the wild

Abstract

Dynamic Virtual Machine (VM) consolidation dynamically adapts VM resource allocation to resource demands promising significant cost benefits for highly variable enterprise workloads. In this work, we analyze large enterprise workloads with the goal of understanding how effective are the VM consolidation variants in real world. We observe that burstiness in memory demand is much lower than the burstiness in CPU demand. Further, memory is the more constrained resource in virtualized servers, significantly reducing the potential gains due to dynamic consolidation. We study consolidation planning in four very large data centers and observe that the savings in facilities cost due to dynamic consolidation over static consolidation is not as large as estimated by past studies. Further, the savings over intelligent semi-static consolidation are surprisingly modest in most cases, putting a question mark over the applicability of dynamic consolidation in real world.