A Semantic-Aware Cache Prefetching Mechanism for Disk Array

Cache prefetching is a highly effective technique for improving I/O performance of disk array. A semantic-aware cache prefetching mechanism is designed to improve cache hit rate of disk array. The mechanism can identify some important properties of each block on the disk, and utilize that information to determine whether the block is live or dead. The allocation status (live or dead) of block is a kind of semantic information of blocks in disk array. Knowledge about semantic information of blocks can enable the mechanism to selectively cache only those live blocks. Simulation experiments have been carried out to evaluate performance of semantic-aware cache prefetching mechanism. The results show that the proposed mechanism gives a better hit rate than mechanism without semantic information for a large number of read requests. The mechanism is especially efficient when the disk capacity utilization rate is low.