Abstract: Virtual Machine (VM) migration is an important activity which is required for managing virtualized environment, load balancing, power saving and maintenance activities like management of faults due to resource failures etc. For virtualization, practitioners have used mostly proprietary hypervisors as compared to open source hypervisors because they consider open source hypervisors have less functionality. However, some research studies indicate that open source hypervisors may be a good alternative without compromising on functionalities needed for virtualization. To confirm the same, an experiment has been carried out on two virtualization systems Kernel-Based Virtual Machine KVM (open source hypervisor) and Xen (proprietary hypervisor) to evaluate their respective performances total migration time, downtime etc. using VM live migration technique.