Efficient Storage Synchronization for Live Migration in Cloud Infrastructures

Live migration of virtual machines is an important issue in Cloud computing environments: when physical hosts are overloaded, some or all virtual machines can be moved to a less loaded host. Live migration poses additional challenges when virtual machines use local persistent storage, since the complete disk state needs to be transferred to the destination host while the virtual machines are running and hence are altering the disk state. In this paper, several approaches for implementing and synchronizing persistent storage during live migration of virtual machines in Cloud infrastructures are presented. Furthermore, the approaches also enable users to migrate swap space, which is currently not possible on most virtual machine hypervisors. Finally, measurements regarding disk synchronization, migration time and possible overheads are presented.