Allocation of Virtual Machines in Cloud Data Centers – A Survey of Problem Models and Optimization Algorithms∗

Data centers in public, private, and hybrid cloud settings make it possible to provision virtual machines (VMs) with unprecedented flexibility. However, purchasing, operating, and maintaining the underlying physical resources incurs significant monetary costs and also envi-ronmental impact. Therefore, cloud providers must optimize the usage of physical resources by a careful allocation of VMs to hosts, continuously balancing between the conflicting require-ments on performance and operational costs. In recent years, several algorithms have been proposed for this important optimization problem. Unfortunately, the proposed approaches are hardly comparable because of subtle differences in the used problem model. This pa-per surveys the used problem formulations, highlighting their strengths and limitations, also pointing out the areas that need further research in the future