Assessing multi-version systems through fault Injection

Abstract

Multi-version design (MVD) has been proposed as a method for increasing the dependability of critical systems beyond current levels. However, a major obstacle to large-scale commercial usage of this approach is the lack of quantitative characterizations available. Fault injection is used to help seek an answer this problem. Fault injection is a phrase covering a variety of testing techniques that can be applied to both hardware and software, all of which involve the deliberate insertion of faults into an operational system to determine its response. This approach has the potential for yielding highly useful metrics with regard to MVD systems, as well as giving developers a greater insight into the behaviour of each channel within the system, k this research, an automatic fault injection system for multi-version systems called FITMVS is developed. A multi-version system is then, tested using this system, and the results analysed. It is concluded that this approach can yield several extremely useful metrics, such as metrics related to channel sensitivity, channel sensitivity to common-mode error, program' scope sensitivity, program scope sensitivity to common-mode error, error frequency distribution and common-mode error frequency distribution. In addition to this, the analysis of the multi-version system tested indicates that the system has an extremely low probability of experiencing common-mode error, although several key points in channel code are identified as having higher sensitivity to faults than others.