Research On The Virtual Machine Hot Standby System Remus Based On Xen In Cloud Computing

Cloud computing develops from grid computing and utility computing,implementing to use the resource as needed. Virtualization is the cornerstone torealize cloud computing. Virtualization technology allows to run on a singlecomputer with multiple operating system instances simultaneously, and eachoperating system instance shares hardware resources of physical machine. Itenhances the overall utilization of resources largely. However, it proposes higherrequirement for the availability of virtual machine that multiple virtual machinesare deployed on a single physical machine. When the physical machine deployedvirtual machines damages, ensuring the continuous application of virtual machineand enhancing the availability of virtual machine become the focus of attention.In some cases, the high-availability of virtual machine is considered moreimportant than its performance.This paper describes cloud computing and Xen virtualization technology. Onthis basis, expound the Remus virtual machine hot standby system with Xen indetail. Remus adopts continuous copy to realize state synchronization betweenprimary and backup virtual machine. Continuous copy works well in null and lowload. However, it can’t work well for more dirty pages and downtime whenlocating heavy load. For this problem, this paper proposes the thought ofpre-transfer to improve original Remus. Pre-transfer a part of memory pagesduring the primary virtual machine running to reduce the number of transferredmemory pages in downtime. The thought of pre-transfer divides transferredmemory pages into two parts: a part is transferred in the stage of primary virtualmachine running, called pre-transfer pages; The others are transferred in thephase of primary virtual machine stopping, called stop-transfer pages. Topre-transfer pages, memory selection algorithm is applied to choose memorypages to be transmitted during pre-transfer stage to escape from duplicate transmission in the stage of stop-transfer. To stop-transfer, memory compressionalgorithm based on the memory page features is used to compress memory pages.Compress adaptively the memory pages of virtual machine on the basis of theircharacteristics on the purpose of reducing the time of stop transmission.Build experimental environment to test the rationality of the design of thisarticle. Test the downtime of Remus system in different memory size, timeintervals and dirty rate. The experimental results show that the improved Remussystem with memory selection and memory compression algorithm reduces thedowntime at an average of25.89%, the highest reduction can reach36.02%. Itcan be concluded that the improved Remus system effectively promotes theavailability of original Remus system.