An empirical study of a CDC 844-41 disk subsystem

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Abstract

Three methods (seek overlap, seek arm scheduling, static file repositioning) for improvement of disk subsystem performance are reviewed. Detailed measured data are reported for seek time, probability of zero-length seek, latency, and transfer time, for a 12-spindle CDC 844-41 disk subsystem shared between two CDC Cyber 170/750 central processors. The probability of zero-length seeks is shown to be high, and the spindle queue lengths are observed to be low. The transfer time data are very different from the data published by others for IBM systems. A detailed simulation model of the measured system is shown to validate. This model is then used to demonstrate that seek arm scheduling is unlikely to produce much improvement, that static file repositioning can improve performance by about 20%, and that seek overlap can almost double the interactive capacity of the system measured.

References (33)

  • A.J Smith

    Input/output optimization and disk architectures: a survey

    Performance Evolution

    (1981)
  • J.W Atwood et al.

    An analysis of a CDC 844-41 disk subsystem

  • Y Bard

    A model of shared DASD and multipathing

    Comm. ACM

    (1980)
  • R.S Brice et al.

    Feedback coupled resource allocation policies in the multiprogramming-multiprocessor computer system

    Comm. ACM

    (1978)
  • J.C Browne et al.

    The interaction of multi-progamming job scheduling and CPU scheduling

  • E.G Coffman et al.

    Analysis of scanning policies for reducing seek times

    SIAM J. Comput.

    (1972)
  • Control Data Corporation

    NOS Version 1 Reference Manual

    (1978)
  • P.J Denning

    Effects of scheduling on file memory operations

  • D.V Foster et al.

    A language for analysis of queueing models

  • H Frank

    Analysis and optimization of disk storage devices for time-sharing systems

    J. ACM

    (1969)
  • S.H Fuller

    Minimum-total-processing time drum and disk scheduling discipline

    J ACM

    (1974)
  • M Hofri

    Disk scheduling: FCFS vs. SSTF revisited

    Comm. ACM

    (1980)
  • J.H Howard

    A large scale dual operating system

  • J.H Howard et al.

    The UT-2D operating system event recorder

  • J.H Howard et al.

    EVENTD-UT-2D event tape summary/dump

  • IBM Corporation, IBM system/360 operating system: input/output supervisor, program logic manual, Publication number...
  • Cited by (1)

    View full text