On-Demand Deployment of Virtual Machines Based on Optimized COW Virtual Block Device

The COW(Copy-on-Write) virtual block device(VBD) is very helpful for fast virtual machine(VM) deployment in large-scale virtual machine environments. This paper presents an optimization approach for the COW VBD in virtual machine monitor(VMM),which can improve the access performance of COW disks and can make many small-sized COW disk images to reduce the cost of VM deployment over the network. Based on the optimized COW VBD,the paper also presents an on-demand VM deployment scheme and the solutions to the key problems of the scheme. Based on Linux system,the authors have implemented the optimized COW VBD in QEMU virtual machine monitor and an on-demand VM deployment prototype system. Experiments show that the optimized COW VBD,the effective working set-based deployment optimization and the COW disk reclamation approach,etc can effectively support low-cost,on-demand VM deployment in virtual machine environments.