Abstract: The existing memory-based virtual machine ( VM) migration technology requires network-disk shared between source side and destination side, which results performance degradation greatly from poor network quality, and the VM migration can not be implemented without shared network-disk environment. To solve these problems, in view of the high-availability, high-performance, security and stability displayed by VM-disk, which acts as the encapsulation of VM persistent running state,a new migration strategy based on VM disk was proposed and implemented. A virtual disk driver named DiskMig was designed to migrate VM disk and ensure its consistency during migration process, and a new algorithm Transfer on Demand with Forward-ahead(TOD& FA) was presented to synchronize disk differences between source and destination fast. An effective storage structure bitmap was adopted by DiskMig system to record and search massive I/O offset information during migration with only constant time complexity. The experiment demonstrates that the performance of VM and its applications brought by the DiskMig system was only 5 percent degraded,thus the VM migration including its disk is implemented efficiently.

Key words: Virtual machine migrate, Virtual machine, Consistency, Virtual disk driver