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.%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.
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