Software architecture reliability analysis using failure scenarios

With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components and usually assume the availability of a running system. Software architecture analysis methods aim to analyze the quality of software-intensive system early at the software architecture design level and before a system is implemented. We propose a Software Architecture Reliability Analysis Approach (SARAH) that benefits from mature reliability engineering techniques and scenario-based software architecture analysis to provide an early software reliability analysis at the architecture design level. SARAH defines the notion of failure scenario model that is based on the Failure Modes and Effects Analysis method (FMEA) in the reliability engineering domain. The failure scenario model is applied to represent so-called failure scenarios that are utilized to derive fault tree sets (FTS). Fault tree sets are utilized to provide a severity analysis for the overall software architecture and the individual architectural elements. Despite conventional reliability analysis techniques which prioritize failures based on criteria such as safety concerns, in SARAH failure scenarios are prioritized based on severity from the end-user perspective. SARAH results in a failure analysis report that can be utilized to identify architectural tactics for improving the reliability of the software architecture. The approach is illustrated using an industrial case for analyzing reliability of the software architecture of the next release of a Digital TV.