  Virtualization technology reduces cloud operational cost by increasing cloud
resource utilization level. The incorporation of virtualization within cloud
data centers can severely degrade cloud performance if not properly managed.
Virtual machine (VM) migration is a method that assists cloud service providers
to efficiently manage cloud resources while eliminating the need of human
supervision. VM migration methodology migrates current-hosted workload from one
server to another by either employing live or non-live migration pattern. In
comparison to non-live migration, live migration does not suspend application
services prior to VM migration process. VM migration enables cloud operators to
achieve various resource management goals, such as, green computing, load
balancing, fault management, and real time server maintenance. In this paper,
we have thoroughly surveyed VM migration methods and applications. We have
briefly discussed VM migration applications. Some open research issues have
been highlighted to represent future challenges in this domain. A queue based
migration model has been proposed and discussed to efficiently migrate VM
memory pages.
