Software Reliability

Primary reliability factors for software have been reported by Sally Dudley to be [1]:

1. Defects in the code
2. Defects in the interfaces with other code
3. Operational defects which cause changes to defect-free code

We can add to this list sustainability. Sustainability is an attribute which defines the life-time of a software system and its continuity. Once a software system becomes obsolete, its reliability could be greatly impacted. This makes common sense, a software system which is operating on an obsolete hardware system that might no longer be supported by its manufacturer would have a large impact on the reliability of the software.

Sustainability of software systems could occur for various reasons. Sandborn and Plunkett summarized three main causes of software obsolescence [2]; functional, technological and logistical factors.


References:

[1] W. Ireson, C. Coombs, "Handbook of Reliability Engineering and Management", Mc Graw-Hill, 1988.

[2] P. Sandborn and G. Plunkett, "The Other Half of the DMSMS Problem - Software Obsolescence", DMSMS Knowledge Sharing Portal Newsletter, vol. 4, issue 4, pp.3 and 11, June 2006.