Towards Improving Data Center Utilisation By Reducing Fragmentation

Many enterprise organizations, like large ecommerce platforms, are consolidating their ICT infrastructure on private clouds to harness cloud properties of scalability and elasticity. Administratively many of these cloud deployments use pre-defined VM sizes to ease effort of use and placement. With this sizing, workloads' requirements poorly match with the offered sizes leading to poor VM and host utilisations. This paper proposes alternate VM sizing approaches to overcome this and compares internal, external resource fragmentation in each case. To evaluate this, utilisation traces from the private cloud of Flipkart, having thousands of servers and VMs are used. Evaluations show that applications as well as host utilisation benefits accrue by customising VM sizes to application requirements. We also show how VM sizes and host configurations influence consolidation ratios and utilisation.