Virtualization technology is currently becoming increasingly popular and valuable in cloud computing environments due to the benefits of server consolidation, live migration, and resource isolation. Live virtual machine migration is the process of moving virtual machine from one physical host to other without disturbing the users. Effective migration of virtual machine requires the movement of storage, memory, process states and network connectivity. Live migration of virtual machines has been a powerful tool to facilitate system maintenance, load balancing, fault tolerance, and powersaving, especially in clusters or data centers. During the process of migration, services are running in the virtual machines, hence it requires minimum total migration time, down time in order to avoid service degradation. This paper introduced discussion of various techniques for effective live virtual machine migration to reduce both downtime and total migration time. This paper also present the various scenarios, where the live migration of virtual machines can takes place.