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Seek Distances in Two Headed Disk Systems
 Info. Proc. Letters
, 1996
"... We make a correction to the calculation of mean seek time in a recent algorithm of intelligently positioned two headed disk systems. We also introduce a new two headed disk system with better mean seek time. 1 Introduction Two headed disk systems, as categorized in [3], may have (a) two arms autono ..."
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We make a correction to the calculation of mean seek time in a recent algorithm of intelligently positioned two headed disk systems. We also introduce a new two headed disk system with better mean seek time. 1 Introduction Two headed disk systems, as categorized in [3], may have (a) two arms autonomously controlled [2,4], (b) two arms and a single controller [1] and, (c) a single arm with two fixed heads on it [4,5]. In calculating seek distances for intelligently positioned two headed systems in [4] authors ignore jockeying time of the dummy head. In this paper we recalculate the seek distance considering the penalty for jockeying. A new two headed disk system has been introduced in which the disk surface is partitioned into two equal halves and each dedicated head serves the half it is in while the other tries to occupy the center of its half. 2 Preliminaries Consider that a disk is a linear storage medium consisting of N cylinders, each of which is divided into a number of sectors...
Information Processing Letters Seek distances in twoheaded disk systems
, 1994
"... We make a correction to the calculation of mean seek time in a recent algorithm of intelligently positioned twoheaded disk systems. We also introduce a new twoheaded disk system with better mean seek time. ..."
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We make a correction to the calculation of mean seek time in a recent algorithm of intelligently positioned twoheaded disk systems. We also introduce a new twoheaded disk system with better mean seek time.
Probability Distributions for Seek Time Evaluation
"... In this work, two known probability distributions based on the replacement model, namely, the MaxwellBoltzmann and BoseEinstein ones, are examined. Each of these distributions is assigned to a specific case of query processing, which is known in the literature as batching on primary key values or ..."
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In this work, two known probability distributions based on the replacement model, namely, the MaxwellBoltzmann and BoseEinstein ones, are examined. Each of these distributions is assigned to a specific case of query processing, which is known in the literature as batching on primary key values or secondary key retrieval, respectively. These distributions are applied in evaluating the expected distance traveled by the read/write heads in disk searching. Two new probability distributions are derived, based on the previous ones, which are involved in the evaluation of the expected number of the cylinder hits. Therefore, seek time evaluation is faced globally. Numerical results are given. 1.