Designing And Implementation Of Distributed Extent Lock Based On Zookeeper

The distributed file systems solve most of the storage and management problems, but they also bring out the consistency problem when multiple clients accessing the same data. However, the distributed lock ensure different clients access the correct data in the server. When multiple clients access different extent of the same file, the file lock causes many conflicts. While the extent lock give different extent for different lock. Thus, there are less conflict locks. The extent lock can be more effic ient.Explored the distributed lock management in several distributed file system and their advantages and disadvantages. Combined with the problems of the lock management in the object based distributed flie system Cappella, which is an independent development product in our laboratory, designed a distributed extent lock based on Zookeeper, to essure the consistency access to the object in the file system.Combined with Zookeeper’s distributed coordination services, implemented the hierarchical structure of directory in the server, the application and the release of the distributed extent lock and the local lock cache. Then analyzed the use of extent lock in Cappella file system in detail. Especially focused on the problems of positive lock in the sequential access mode, proposed the first fit positive extent lock. When the first lock is insert into the granted list, it can get the whole file extent. And then, if a conflict lock occurred, this lock’s extent will not change. This machanism can decrease the number of conflicts, and increase the performance. Besides, when the lock requests are very intensive, there will be many conflict callbacks. According to the conflict situation of the coming lock, delete the conflict lock directly after it is finis hed.According to the system tests results, the distributed extent lock doesn’t influence the Cappella’s aggregation bandwidth. With the first fit positive extent lock, can decrease the conflict number and improve the efficiency of lock requests in the sequential alternate access mode. And then, it is better than Lustre file system. In addition, the extent lock’s optimization in intensive access mode is useful.