| Virtualization is a faithful and isolated reproduction of an entire architecture in software which provides the illusion of a real machine to all operating systems running above it respectively. Virtualization is a hot topic in industrial and academic research, and one of the fastest glowing technologies.Virtualization is applicable in many computer related areas. It can be served as a solution of software compatibility, server consolidation, application consolidation, in order to cut down maintenance and management overhead of information systems. Based on virtualization technology, the live migration of operating system with its applications makes online maintenance and online upgrade of servers possible, and becomes an innovatory tool for building high reliability systems. Virtualization is also a means for grid computing and distributed computing.In this thesis, current research status of virtual machines are summarized, the supports for virtualization by modern CPU are analyzed, the theory and key technologies of virtual machine system are investigated, a profound study of live migration of Xen VMs is discussed in detail by reading source code. The implement of live migration are addressed, including contents to be transferred and the steps to migrate a VM. The judgment for WWS and the re-structure of shadow table are studied. The performance of live migratting a VM with different workloads is evaluated and tested, and the experiment results are analyzed. The tests prove that live migration is more applicable and superior than non-live migration (static migration), and expose the influence of application running on VM to live migration. |
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