Jelena Mamčenko Operating Systems Lecture Notes on Operating Systems 45 27 Data structure in disk. 27.1 Disk Structure and Partitions A hard disk is physically composed of a series of flat, magnetically coated platters stacked on a spindle. The spindle turns while the heads move between the platters, in tandem, radially reading/writing data onto the platters. Fig. 3. Physical Disk Structure 27.2 Disk tracks, cylinders, and sectors A disk is divided into tracks , cylinders , and sectors . A track is that portion of a disk which passes under a single stationary head during a disk rotation, a ring 1 bit wide. A cylinder is comprised of the set of tracks described by all the heads (on separate platters) at a single seek position. Each cylinder is equidistant from the center of the disk. A track is divided into segments of
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