Patent ID: 6877070

Claim:
A method for implementing command queue ordering with prefetch benefit determination comprising the steps of: for each command in a hard disk drive command queue, calculating a rotational position optimization (RPO) score; calculating a prefetch benefit of each said command in said hard disk drive command queue within a working partition including the steps of multiplying a cache hit probability resulting from a prefetch by an average time required to execute a non-cached command to calculate said prefetch benefit, calculating said cache hit probability resulting from said prefetch; wherein the step of calculating said cache hit probability resulting from said prefetch is represented by: P (cache hit)=(net cache addition)/(net partition size) where said net cache addition equals a net amount of valid data to be added to a cache as part of read and prefetch operations and said net partition size is a calculated variable; modifying said RPO score of said identified commands in said hard disk drive command queue within said working partition utilizing said calculated prefetch benefit; and identifying a best RPO score for selecting a next command in said hard disk drive command queue to execute.