A. software reliability methodology using software sneak analysis, SW FMEA and the integrated system analysis approach

A design analysis on system software can be very beneficial towards obtaining a highly reliable system. For a system to be reliable, it is important to know how the system operates with and without failures to create compensating provisions that could increase overall reliability. Software does not "'fail" like hardware where there is an object that can be examined, analyzed and improved upon. Software failures are abstract and consist of logic errors or program paths not intended by the system designers at a specific moment of time. Software based systems have been known to produce these anomalous, unexpected outputs at undesirable times not due to any hardware failures. These unexpected anomalies can be classified as software sneak conditions. To provide full coverage in the analyses approach, a software failure modes and effects analysis (SW FMEA) is also performed to examine system effects if functions of the software did not operate as intended because of a software failure. This paper introduces the integrated system analysis (ISA) method of performing a software sneak analysis. The ISA process and tools that capture and model the software functionally and are then used to perform the SW FMEA. The approach discussed using the ISA tools, software sneak analysis and a SW FMEA have been performed and the results of one analysis is presented.