Math @ Duke

Publications [#236031] of Robert Calderbank
Papers Published
 Calderbank, AR; Jr, EGC; Flatto, L, Note extending the analysis of twohead disk systems to more general seektime characteristics,
IEEE Transactions on Computers, vol. 38 no. 11
(1989),
pp. 15841586 [doi]
(last updated on 2018/11/17)
Abstract: The authors analyze a model of a movablehead disk system with two read/write heads maintained a fixed distance d apart on each arm. Successive requestaddresses are assumed to be independent random variables, uniformly distributed over the set of cylinders. The purpose of the analysis is to find that value of d which minimizes the expected seek time per request, assuming that seek time varies linearly with the distance z traveled by the heads. The authors extend an earlier analysis of this model to more general seektime characteristics which take into account nonlinear acceleration effects. Detailed results, combining both analysis and simulation experiments, are presented for seek times linear in zα, 0 ≤ α ≤ 1. An unexpected result of the study was that the value of d which minimizes expected seek time is very nearly independent of α.


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