网络存储系统中低开销高性能的第二级缓存替换算法的研究

Research on the Second Level Buffer Cache Replacement Algorithm with Low Miss Penalty and High Performance for Networked Storage System

针对网络存储访问特性所带来的第二级缓存性能降低的问题,提出了一种高性能的第二级缓存替换算法。本算法采用顺序页面检测机制,能根据缓存页面顺序程度的不同做出替换选择,以减少缓存失效引起随机访问磁盘的次数,避免不必要的磁头寻道和旋转开销,从而改善整个存储系统的性能。实验结果表明,在多种缓存大小下,本文算法能显著降低有效响应时间,使网络存储系统达到更优的性能。

Early researchers have observed that second level buffer caches commonly suffer from severe performance degradation,because the networked storage servers have special access patterns.To address the critical issue,this paper presents a novel cache replacement algorithm using a new mechanism called sequentiality detecting to achieve high performance.The attribute named sequentiality is defined for buffer pages to make a replacement decision：sequential pages with a high sequentiality value are preferred to be discarded rather than the random pages with a low sequentiality value.That is to say,this algorithm can reduce the numbers of random disk access and avoid unnecessary seeking and rotating cost of the disk heads.Our trace-driven simulation results show that it can significantly reduce effective access time and deliver a better performance for a wide range of cache sizes.