A Non-Forced-Write Atomic Commit Protocol for Cluster File Systems

• Published in: Journal of computer science and technology 2014, Vol.29 (2), p.303-315
• Main Author: 邵冰清 张军伟 郑彩平 张浩 刘振军 许鲁
• Format: Article
• Language: English
• Subjects: Artificial Intelligence; Clusters; Computer Science; Consistency; Data Structures and Information Theory; Disks; Distributed processing; Information Systems Applications (incl.Internet); Metadata; Networks; Protocol; Protocol (computers); R&D; Regular Paper; Research & development; Response time; Science; Servers; Servers (computers); Software Engineering; Studies; Theory of Computation; 元数据服务器; 分布式文件系统; 原子; 平均响应时间; 提交协议; 数据一致性; 数据操作; 群集
• ISSN: 1000-9000; 1860-4749
• DOI: 10.1007/s11390-014-1432-y

Distributed metadata consistency is one of the critical issues of metadata clusters in distributed file systems. Existing methods to maintain metadata consistency generally need several log forced write operations. Since synchronous disk IO is very inefficient, the average response time of metadata operations is greatly increased. In this paper, an asynchronous atomic commit protocol （ACP） named Dual-Log （DL） is presented. It does not need any log forced write operations. Optimizing for distributed metadata operations involving only two metadata servers, DL mutually records the redo log in counterpart metadata servers by transferring through the low latency network. A crashed metadata server can redo the metadata operation with the redundant redo log. Since the latency of the network is much lower than the latency of disk IO, DL can improve the performance of distributed metadata service significantly. The prototype of DL is implemented based on local journal. The performance is tested by comparing with two widely used protocols, EP and S2PC-MP, and the results show that the average response time of distributed metadata operations is reduced by about 40%-60%, and the recovery time is only I second under 10 thousands uncompleted distributed metadata operations.