Electrical computers and digital processing systems: memory – Storage accessing and control – Access timing
Reexamination Certificate
1998-07-31
2001-05-22
Kim, Matthew (Department: 2752)
Electrical computers and digital processing systems: memory
Storage accessing and control
Access timing
C711S111000, C710S005000
Reexamination Certificate
active
06237070
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of determining the data layout geometry of a disk drive by applying a novel access pattern and interpretation of the measured results.
BACKGROUND OF THE INVENTION
Modern disk drives store data in blocks with a fixed size. The physical block in a drive are termed sectors. The sectors are arranged in tracks, each track having a fixed number of sectors, and the tracks are arranged in cylinders. Many of today's magnetic disk drives employ zone recording, where all tracks within a zone have the same number of sectors per track. The sectors may be skewed from track to track and from cylinder to cylinder.
These disk drive parameters, namely, a number of tracks per cylinder, number of zones, number of sectors per track in each zone, track skew, and cylinder skew, define the data layout geometry of a disk drive. These parameters affect the performance characteristics of a disk drive. An additional parameter that affects the disk drive performance is the drive's rotational speed. A need arises for a technique with which these disk drive parameters may be quickly and easily determined, for any disk drive encountered.
SUMMARY OF THE INVENTION
The present invention is a system and method for determining the disk drive parameters of any disk drive that may be encountered. By applying a special access pattern to the disk drive and a special technique of interpreting the measured results, the present invention can determine the number of data tracks per cylinder, the number of recording zones, number of sectors per track in each zone, the track skew, the cylinder skew, and the rotational speed of the disk drive.
In order to determine a data layout geometry of a disk drive, access times for a plurality of sectors on the disk drive are measured by alternately performing the steps of: accessing an anchor sector of the disk drive, and accessing a successive sector of the disk drive and measuring a completion time of the access. Parameters related to the data layout geometry of the disk drive are determined based on the measured access times.
In order to determine the parameters, contiguous patterns of the measured access times are detected and gaps between contiguous patterns of the measured access times are detected. Parameters related to the data layout geometry of the disk drive are then determined based on the detected contiguous patterns and gaps in the contiguous patterns of the measured access times.
Gaps of a first size, representing a track skew, and gaps of a second size, representing a cylinder skew, are detected. A number of sectors per track is determined based on a contiguous pattern of access times between two track skew gaps, wherein the number of sectors per track is equal to the number of contiguous access times in the contiguous pattern. A number of tracks per cylinder, which is equal to a number of contiguous patterns of access times between two cylinder skew gaps, is determined. A gap of a third size, representing a revolution is detected and a revolution speed of the disk drive is determined based on the size of the revolution gap.
In another embodiment of the present invention, a plurality of measurements are performed, each performance of a measurement performed using a different anchor sector. A number of sectors per track is determined for each performance of the measuring step, whereby a zone layout of the disk drive is determined. An anchor sector to be used for each performance of the measuring step may be selected from the set {0, M/X, 2M/X, 3M/X, . . . , (X−1)M/X)}, wherein M is the maximum logical block address of the disk drive and X is a positive integer.
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IBM Technical Disclosure Bulletin, Adaptive Skew Optimization, Oct. 1995, pp. 559-562.*
Worthington et al., “On-Line Extraction of SCSI Disk Drive Parameters”, 1995, 146-156.*
Aboutabl et al., “Temporally Determinate Disk Access: An Experimental Approach”, 1998.
International Business Machines - Corporation
Kim Matthew
Morgan & Finnegan L.L.P.
Peugh Brian R.
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