| RAID is present not only as a sort of storage solution. The I/O performance of RAID directly affects the behavior of storage system. When massive storage booming quickly, the storage interface of host computer is easy to become the system I/O bottleneck. The requests have behaviour of random request model in RAID system that when multiple users are reading large mounts of sequential data at the same time. It will reduce the performance of the system because the routine prefetching just regard the requests as random requests. The research devoted to solve the two problems.As to speed up the data transfer through the host storage interface, LSI53C1010-66, a SCSI controller, which implements the SCSI protocol of Ultra160, works as the interface passway of host computer. The speed of data transfer between SCSI devices is upto 160MB/s implemented by the setting of registers in the SCSI controller and the intercourse of expended SCSI protocol messages. Cache smart prefetch algorithm can analyze the characters of sequential data requests from the random data requests. This algorithm can make sure the maxium of the rate of Cace hit by scheduling right disk Cache and prefetching data from disks. At the same time, this algorithm will count the number of Cache hit in real time, then decide the length of next prefetching, which reducing the cost of prefetching fail at the best. The RAID using Cache smart prefetch algorithm can be applied in more expended data storage environment in case of not reducing the performance.Through adopting the above two kinds of optimization technology, there is certain improvement on I/O performance in the RAID, which can meet the needs of data storage in the environment of actual application better.
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