Analysis and Optimization of Disk Storage Devices for Time-Sharing Systems

Abstract

A major limitation for time-sharing systems is the time delay encountered in transferring records between central “fast” memory and peripheral memory devices. In this paper the transfer characteristics of disk storage devices are considered. Expected seek time and expected rotational latency are taken as measures of performance for the disk. The following aspects of disk files and their behavior are considered: the speed profile of the positioning mechanism and its effect on seek time; effects of the probability distribution of information stored on tracks; track overflow of records; dynamic queuing strategies; reduction of rotation time by buffered read techniques; and strategies for using multiple-arm devices.