基于广域存储系统的副本技术研究

Research on Data Replication in Wide-Area Storage System

针对广域网高延迟、低带宽的特性给广域文件系统访问带来的性能影响问题,提出了一种不依赖于底层文件系统、能够加速广域文件系统读写访问的缓存策略。该策略支持基于区间粒度的文件数据缓存及访问,并支持元数据本地缓存;并提供基于阈值的容量管理功能,采用超时与最终一致相结合的方式维护缓存的一致性。最后使用典型的文件I/O基准测试工具和元数据性能测试工具对该缓存策略进行了评测,实验结果表明:该缓存策略减少了客户端与服务器的交互次数,给广域文件系统的数据访问带来了明显的性能提升,当缓存命中时其数据的读写性能与本地文件系统相近。

To address the performance issues over high latency, low bandwidth wide - area links, we propose a caching strategy which is independent of the underlying local file systems and can speed up data access in wide - area file systems. In our approach, files are cached and accessed at the granularity of extents and can be eliminated on a threshold - based policy ; metadata is also cached locally. With regard to consistency model, it is achieved based on timeout and eventual consistency. We use file I/O benchmark and metadata benchmark programs to validate our approach. Evaluation results demonstrate that our approach reduces interactions between client and server, therefore dramatically increases the overall performance of data access in wide - area environment. The tests also show that if there is a cache hit, it can offer a comparable performance to local file systems.