基于VDL的附网存储快照及在线备份新技术

VDL-Virtual Device Layer:A New Approach for Snapshot and Online Backup

针对现有NAS系统在快照及在线备份技术方面存在的问题,该文提出了一种通过虚拟设备层(VDL:VirtualDeviceLayer)实现了NAS的快照和在线备份技术。在VDL中:通过一个快照盘保存在快照和备份期间系统的写操作,实现NAS的快照和在线备份;以设备驱动模块实现,与具体的文件系统无关,使其适用性更为广泛,并让现有的离线备份软件实现在线备份功能;在驱动模块内部对数据的小写进行了优化,较大的提高了办公/工程环境下工作负载的小写性能;备份的初始化时间几乎可以忽略不计,大大提高了存储系统的可用性;实现了存储虚拟化功能,从而将多个存储接点整合成单一的存储池。通过大量的测试表明,VDL对系统整体I/O性能和应用程序影响很小,同时表现出优良的小写性能,达到了预期的效果。

In order to solve the issues of snapshot and online backup,this paper recommend a method which can implement snapshot by VDL （Virtual Device Layer）.Firstly,through saving write request of operatI/On system on a snapshot disk during system snapshot and backup,VDL can implement snapshot and online backup.Secondly,because VDL is designed through linux device driver module and is independent of file system for wider applicatI/On,the most of off-line backup softwares can achieve online backup now.Thirdly,VDL improves performance for small writes as compared to existing system in office/engineering-workload environment because it optimizes small write request in device driver module.It improves availability of storage system because time can be ignored at the beginning of backup initializatI/On.Finally,it achieves the functI/On of storage visualizatI/On,and thus integrates several storage nodes into one single storage pool.Trough lots of benchmark tests,via applying online backup of storage system,VDL shows superb small write performance of NAS system and have a little influence on the whole NAS I/O performance and user programs.