The Effects of Hotspot Detection and Virtual Machine Migration Policies on Energy Consumption and Service Levels in the Cloud

Managing Cloud resources e ciently necessitates e ective policies that assign applications to hardware in a way that they require the least resources possible. Applications are rst assigned to virtual machines which are subsequently placed on the most appropriate server host. If a server becomes overloaded, some of its virtual machines are reassigned. This process requires a hotspot detection mechanism in combination with techniques that select the virtual machine(s) to migrate. In this work we introduce two new virtual machine selection policies, Median Migration Time and Maximum Utilisation, and show that they outperform existing approaches on the criteria of minimising energy consumption, service level agreement violations and the number of migrations when combined with di erent hotspot detection mechanisms. We show that parametrising the the hotspot detection policies correctly has a signi cant in uence on the workload balance of the system.