Automatic cloud's cluster sizing: Controlling cloud service level agreement violation

Cloud computing creates new business opportunity for small, medium or even large size companies, as it eliminates the need of investing in a huge datacenter in order to operate the environment. The contract between the cloud service provider (CSP) and the lessee is called service level agreement (SLA), which guarantee the quality of service (QoS) that should be fulfilled from the CSP to the lessee. The problem is that an over utilized node may result to SLA violation; However, virtual machine (VM) migration from utilized node to unutilized node or a node in power saving mode can decrease the SLA violation percentage, but potentially increase the cloud's power consumption. Our proposed solution is to automatically modify the number of nodes in each cluster, to find the optimum cluster size based on the current SLA violation percentage, and to be an extension to our previously proposed adaptive power panel, in which the cloud's datacenter is divided into clusters, where different VM migration policies are applied.