Patent ID: 6260108
Filing Date: 2001-07-10
Classification: G06F

Abstract:
In a computer system having a plurality of disk drives each disk drive having an internal disk cache with a non-zero fence parameter value coupled to a host computer via a common bus, a method for estimating read durations, in response to requests to read data blocks stored in said disk drives, the method comprising the steps of:(a) measuring an overhead period corresponding to the time during which a request to read is transmitted to a disk drive via said bus;(b) measuring an expected minimum positioning time corresponding to a disk drive having the shortest positioning time among said plurality of disk drives to locate one of said data blocks;(c) measuring mechanism-to-cache read time corresponding to the time required for said disk drive having the shortest positioning time among said plurality of disk drives to transfer a data portion B.sub.C of said data block to an internal disk cache located in said disk drive having said shortest minimum position time among said plurality of disk drives;(d) measuring the time required to transfer remaining data blocks stored in each of said internal disk caches of the remaining disk drives in said plurality of disk drives to said host at a bus bandwidth; and(e) adding said times measured at steps (a) through (d) to estimate said read duration length.