With the development of hardware and the increasingly complex computer applications, the reuse of software and the increased demand of portability, virtual machine technology have been gradually given attention and continuously develop. In 1998, VMware founded by Stanford University announced the first on PC Virtual PC-software VMware [6]. Although it cannot achieve the portability of software on different hardware platform, it can provide isolation for software
and sharing capabilities for hardware. 2004, VMware and Xen were made VMotion [7] and Live Migration [8] technology, which support the migration of on-line virtual machine, making virtual machines running on the computer system can continuously move from one physical machine to another Physical machine, and the time when the system can not be visited is only about
100ms [8].