Research on availability of virtual machine hot standby based on Xen

As the important measure to ensure the high availability of campus virtual data center, virtual machine hot standby has got comprehensive attention. For low availability caused by intrinsic memory copying technology, this paper proposes pre-transfer based on memory selection algorithm and stoptransfer based on memory compression algorithm. A part of memory pages are pre-transferred during the primary virtual machine running, to reduce the number of transferred memory pages in downtime. Meanwhile, on the basis of program locality, predict the dirty pages rate and pre-transfer dirty pages whose rate are low to refrain from duplicate transmission at the stage of stop-transfer. To stoptransfer, improved memory compression algorithm is used to compress the memory pages on the purpose of enhancing the efficiency of stop transmission. The simulation result shows that the downtime of improved Remus system decreases obviously compared with the original Remus in Xen, especially in the situation of high dirty pages rate and long time interval.