Abstract: To reduce further the speed difference between the external memory and the CPU,and to meet more and more I/O request rate,Cache is introduced in the disk array.The strategy focuses on the organization and management of Cache.Taking use of the Least Recently Used algorithm optimization (LRU) improves Cache hit rate and taking use of the conversion between tree structures reduce disk I/O times in order to improve the overall system performance.The experimental results prove that the strategy has really a significant effect to reduce disk write I/O.