2000 Paper 2 Question 8
Software Engineering I
One means of improving system reliability is to have three or more replicated
systems and act on their majority output. Give two examples of failure that can
be stopped by the mechanism, and two which cannot. At least one of each type
should be illustrated by an actual case history or application. [12 marks]
An engineer attempts to improve the reliability of such a system further by
multiversion programming – by having three separate systems coded by different
teams and possibly in different languages. Discuss what might still go wrong.
[8 marks]
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