Information Technology Reference
In-Depth Information
8
Computer
Reliability
The greatest of faults, I should say, is to be conscious of none.
—- THOMAS CARLYLE
8.1 Introduction
COMPUTER DATABASES TRACK MANY OF OUR ACTIVITIES. What happens when a com-
puter is fed bad information, or when someone misinterprets the information retrieved
from a computer? We are surrounded by devices containing embedded computers.
What happens when a computer program contains an error that causes the computer to
malfunction?
Sometimes the effects of a computer error are trivial. You are playing a game on your
PC, do something unusual, and the program crashes, forcing you to start over. At other
times computer malfunctions result in a real inconvenience. You get an incorrect bill in
the mail, and you end up spending hours on the phone with the company's customer
service agents to get the mistake fixed. Some software bugs have resulted in businesses
making poor decisions that have cost them millions of dollars. On a few occasions,
failures in a computerized system have even resulted in fatalities.
In this chapter we examine various ways in which computerized systems have
proven to be unreliable. Systems typically have many components, of which the com-
puter is just one. A well-engineered system can tolerate the malfunction of any single
component without failing. Unfortunately, there are many examples of systems in which
 
 
 
 
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