Computer Capacity Planning. Theory and Practice

221 Pages·1987·7.625 MB·English

by  Shui F. Lam and K. Hung Chan (Auth.)

Computer Capacity Planning
Theory and Practice
Shui F Lam
Department of Mathematics and Computer Science
California State University
Long Beach, California
K. Hung Chan
Graduate School of Management
University of California, Riverside
Riverside, California
ACADEMIC PRESS, INC.
Harcourt Brace Jovanovich, Publishers
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Copyright © 1987 by Academic Press, Inc.
All rights reserved.
No part of this publication may be reproduced or
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United Kingdom Edition published by
ACADEMIC PRESS INC. (LONDON) LTD.
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Library of Congress Cataloging-in-Publication Data
Lam, Shui F.
Computer capacity planning.
Bibliography: p.
Includes index
1. Computer capacity—Planning. I. Chan, K. Hung.
II. Title.
QA76.9.C63L36 1987 004.2'l 86-32220
ISBN 0-12-434430-5 (alk. paper)
87 88 89 90 9 8 7 6 5 4 3 2 1
Printed in the United States of America
To our Parents, and
Jo May and Jo Kay
ACKNOWLEDGMENTS
The authors wish to express appreciation to the many colleagues and
professional acquaintances who have made helpful comments on this
monograph. We are especially indebted to James Pick of the University
of California, Riverside, Art Gittleman of the California State
University, Long Beach, Ronald Reed and William Denton of Home Savings
of America for their detailed reviews and insightful suggestions for
improvements. We have also received invaluable assistance and ideas
from Tsung-Jen Chiu, Apichart Karoonkornsakul, HeeKyung Sung, and Chris­
tina K.Y. Yau.
An important element in the execution and completion of research
project of this kind is the environment in which the effort took place.
We thank Karl Anatol and Charles Austin of the California State
University, Long Beach and Stepan Karamardian of the University of
California, Riverside for their roles in providing this environment.
Finally, to those hundreds of individuals who responded to our question­
naire survey, we are particularly grateful. We hope that the results of
this research will be helpful to the survey respondents and others in
the field of computer capacity planning.
Any shortcomings of this manuscript are the responsibility of the
authors.
January 1987
Shui F. Lam
K. Hung Chan
vii
COMPUTER CAPACITY PLANNING - THEORY AND PRACTICE
PREFACE
Increased computerization in business data processing has led to
greater reliance on computers in business operations and growing data
processing budgets. Many computer-related matters have become major
management concerns. Satisfactory computer services depend greatly on
the choice of configurations and the amount of capacity available on the
computer system. To monitor and project computer workload and to plan
for changes or expansions of computer configurations to meet future
demand in a cost-effective manner is generally referred to as computer
capacity planning. Because upgrading computer facilities often involves
a large sum of money, improvements in capacity planning can mean sub­
stantial cost savings to the company.
This study examines the theory and practices of computer capacity
planning in a more rigorous manner than previous studies. The first
part of this study summarizes and discusses the theories and techniques
presented in recent literature on computer capacity planning. The
second part focuses on examining the degree of applicability of the
theories and techniques and how different organizations may adopt dif-
xiii
xiv Preface
ferent capacity planning methods. It also identifies ways to improve
the applicability of the theory and the quality of the practice on com­
puter capacity planning. A questionnaire was used to collect the
necessary empirical evidences for this study.
The approach taken in this monograph should make it a useful
reference for a wide range of readers. Instead of using a "cookbook"
style showing simply how to do capacity planning, we emphasize on as­
sessing the usefulness of the various approaches and techniques in
capacity planning. The information provided in this monograph should
be of interest to analysts and managers who are faced with the practical
reality of computer capacity planning. It should broaden their under­
standing of this function by knowing how other companies carry out this
function and what techniques are available in the literature that can be
used to improve results. As management advisers, internal and external
auditors as well as other quality assurance personnel should also obtain
insight on how to measure, evaluate, and improve performance of their
own or their clients' computer facilities. Equipment manufacturers and
software developers should find the results of this study useful as they
provide direct consumer information that will help guide the development
of their new machines or new software packages. An essential way to
assess consumer behaviors is to contact the consumers directly. As far
as we can ascertain, this is the first study on computer capacity plan­
ning that directly solicits and analyzes a wide range of consumer infor­
mation in a systematic and scientific manner.
Researchers may use the survey results to assess the future direc­
tion of research in computer capacity planning as these results provide
Preface xv
insight into the degree of applicability of the various techniques under
different business environments. Finally, for students in computer
science, information management and accounting/auditing, we offer a con­
cise description of the principles of computer capacity planning. The
data and analysis of the practices enable students to better appreciate
the usefulness of the capacity planning techniques in different
circumstances.
LIST OF FIGURES
Figure 2.1 A Queueing Network Model with a Terminal 61
-Driven Workload (in Section 2.8.3).
Figure 3.1 Sample Workload Graph (in Section 3.2.1). 74
Figure 3.2 Workload Versus Capacity (in Section 81
3.2.3).
Figure 3.3 Workload Forecasts Assuming Steady Growth 113
(in Section 3.3.11).
Figure 3.4 A Queueing Network Model for Three 115
Workload Classes (in Section 3.3.11).
xvii
LIST OF TABLES
Table 1.1 Increase in Sales of the Ten Largest Computer 4
Companies (in Section 1.1).
Table 3.1 Combining Interactive and Batch Components into 116
One Class (in Section 3.3.11).
Table 3.2 Measurement for the Database and Data Entry 117
Workload (in Section 3.3.11).
Table 3.3 Notations and Formulae for a Mixed Queuing 119
Network Model (in Section 3.3.11)
Table 3.4 Performance Measures Calculated from the 124
Queueing Network Model (in Section 3.3.11).
Table 4.1 Usable Responses to the Questionnaire Survey 141
on Computer Capacity Planning Practices (in
Section 4.3).
Table 4.2 Overall Ratings for Questions 2 to 8 in the 143
Questionnaire Survey (in Section 4.4).
Table 4.3 Analysis of Variances for Overall Mean 144
Ratings (in Section 4.4).
Table 4.4 Multiple Comparisons Using the Ryan-Einot- 145
Gabriel-Welsch F Test (in Section 4.4).
Table 5.1 Breakdown Among Respondents Based on 168
Different Environmental Characteristics
(in Section 5.2).
Table 5.2 Mean Ratings by Group Based on the Four Most 174
Significant Environmental Factors (in Section
5.4).
Table 5.3 F Test (One-Way Analysis of Variance)for the 176
Difference in Mean Ratings (in Section 5.4).
Table 5.4 Specific Effects of the Four Most Significant 178
Environmental Factors on the Five Critical
Capacity Planning Issues (in Section 5.4).
Table 5.5 Mean Ratings by Industry (in Section 5.5). 190
XIX
CHAPTER 1
ISSUES AND OVERVIEW
1.1 The Significance of Computer Capacity Planning
Electronic computing is a relatively new industry. In a history of
thirty some years, electronic data processing has been ingrained into
many aspects of people's daily life and certainly has established a
strong foothold in business and non-business organizations. With more
and more data stored electronically, more operations under computer
guidance or control, and more users relying on computers to carry out
their functions, it is inconceivable for many companies to be able to
continue normal operations without the computer. The availability,
reliability, serviceability, ease of use, rate of response, and other
computer related matters have become major management concerns. As more
operations are being computerized and more users are gaining access to
the computer through their terminals, computer functions are very
visible and computer performance is under close scrutiny. Data process­
ing departments are often expected to provide satisfactory services in
the most cost-effective manner.
1