Modelling Software Operational Reliability 
under Partition Testing



Yinong Chen
Department of Computer Science
University of the Witwatersrand, Johannesburg
2050 Wits
SOUTH AFRICA
email: yinong@cs.wits.ac.za
fax: +27 - 11- 339 7965
tel.: +27 - 11- 716 3304

Full FTCS-28 Paper in Postscript File


Abstract
Operational reliability of programs depends upon many factors imposed 
by design, testing, and operation of programs. In the testing stage, 
the main imperfect factors which can affect operational reliability 
are faults, testing time, fault correction, testing profile and 
operation profile. The modelling process proposed in this paper 
takes all these factors into account. It consists of two testing 
stages and one operational stage. In the testing stages, partition 
testing is used to evaluate the reliability growth. Based on the 
profile coverage between testing and operational profiles, a method 
is found to partition the input domain, so that the testing profile 
can follow the given operational profile of a program. In the 
operational stage, the reliability model uses the remaining faults 
from the testing stages as the source of unreliability. Different 
manifestations of faults in testing and operational stages, due to 
different testing and operational profile, are considered. As an 
application of the model, the reliability sensitivity to the imperfect 
profile coverage is studied. The analytical results agree with the 
experimental results from other researchers.
A large program example is tested by use of this model and results 
are compared with existing work.

Keywords -- reliability growth, operational reliability, 
profile coverage, software fault model.