基于镜像的在线文件系统检查工具的研究与实现①

摘要

This paper designs and implements OnlineFSCK (On-Line File System Checker), which checks the file system while it is online without modifying the in-kernel file system codes. The file system can continue providing service while it is being checked by OnlineFSCK. This paper proposes and implements an runtime imaging algorithm which, combined with the existing file system checkers, can provide us the ability to check the consistency of the existing running file systems. The prototype is implemented for ext3 file system. Experiments shows that our OnlineFSCK solution can guarantee the correctness as traditional file system checkers while keeping the performance of the production system neglectable impacted. As there is no need to modify the in-kernel codes to support it, Online FSCK can be easily extended to support other file systems.%　　设计和实现了一种全新的在线文件系统检查工具-OnlineFSCK(On-Line File System Checker)。 OnlineFSCK可以对在线的文件系统进行一致性检查。利用OnlineFSCK对文件系统进行检查时，文件系统可以继续正常提供服务。提出和实现了一种对在线文件系统生成镜像的算法，并将这个算法与现有的文件系统检查工具相结合，最终达到对在线文件系统进行检查的目的。针对ext3文件系统实现了OnlineFSCK的原型，实验结果表明， OnlineFSCK 在满足对性能的要求的前提下，能够达到与传统文件系统检查工具相同的检查能力。 OnlineFSCK的实现中没有修改文件系统的内核源码，可以扩展支持多种文件系统。