The Research And Implementation Of Large-scale Virtual Machine Image Storage System Based On Multi-level Cache

IaaS(Infrastructure as a service) models in clouds provide services for users in the form of virtual machines. Virtual machines play a significant role in cloud computing. Hardware virtualization technology implemented by Intel and virtual machine management, such as Xen or KVM, largely reduced the implementation cost of the virtual machine itself. With the continuous expansion of cloud data center, virtual machine images storage system has become a very important part. It has a great influence in both deploying cost of virtual machines and run-time performance of applications.Different from the solutions adopted in traditional data center, where SAN or other centralized storage are deployed, MADStor(multi-level cache-based virtual machine image storage system) uses a distributed cooperative caching architecture. In addition to reducing costs, it can avoid being affected by network bandwidth bottleneck in single node. Furthermore, MADStor optimizes network load imbalance in compute nodes, comparing the general collaborative storage system, to avoid I/O bottlenecks. MADStor adopts two disk caches on compute nodes, which brings data sharing and avoids the phenomenon of dirty data. Meanwhile, double deduplication strategies are proposed to reduce storage consumption in compute nodes. MADStor optimizes chunk addressing techniques in distributed object storage system. According to network load distribution, mapping information based on the object name would be dynamically adjusted. And, MADStor stores the mapping information in memory based on contents of objects to increase virtual machine I/O performance.Experimental results show that MADStor has a better performance, compared with traditional centralized storage and the mainstream distributed collaborative system, especially in the situation that the network load is distributed unevenly.