Research And Improvement Of Storage Virtualization Based On Xen

With the development of software and hardware technologies, virtualization has become one of the fastest developed technologies and is now a hot spot in computer science. Xen is an outstanding open source virtual machine monitor. Compared to other software, Xen has the advantage of open source and high performance. So we choose Xen as our research target and research the theory and implementation of Xen's storage virtualization in deep. After the research, we bring forward methods to improve Xen's storage virtualization system.In this paper, we have very deep research on Xen's file-based storage virtualization; we analyze the principle and process for a virtual machine to access the disk in detail. And we also discuss the influence of different I/O schedulers on the performance of virtual machines accessing the disk. We analyze the most suitable schedulers for different types of workloads. There are some problems with Xen's current scheduler:Current CFQ scheduler cannot guarantee the bandwidth quantificationally, which is very important for the performance of many services. In order to improve this, we introduce a dynamic-priority scheduling scheme base on feedback mechanism which can guarantee bandwidth quantificationally and make system resources be allocated more reasonably among virtual machines. We also improve CFQ scheduler for better usage of the dynamic I/O priority scheme.By experiments and analysis, we validate the feasibility of the improved virtual disk scheduler. Most importantly, bandwidth every virtual machine needs can be guaranteed. And there is no obvious degradation caused by the improvement.