Unveiling the resource consumption overhead of virtual machine consolidation in data centers

In recent years, virtualization technologies are applied to data centers for resource sharing. Virtual Machine Monitor (VMM) can consolidate virtual machines (VMs) running on multiple physical servers onto a single one via live VM migration, consequently improving energy efficiency of data centers. VM consolidation is usually modeled as a bin packing problem aiming at minimizing the number of servers being used. However, resource consumption overhead of consolidating VMs is seldom considered in existing approaches. In this paper, the overhead is defined as the resource consumption difference between the server and all the VMs running on it. We theoretically and experimentally prove that under the realistic constrains, this overhead exists and remains steady with the increasing of consolidating VMs. We also propose Margin Reserved Consolidation (MRC) algorithm to supplement existing works. Besides, we conduct experiments to validate the overhead. Experiments based on a representative benchmark show that 11.7% of the server's CPU resource is occupied by the overhead averagely.