Tutorial: Advanced fault tree applications using HARP

Reliability analysis of fault tolerant computer systems for critical applications is complicated by several factors. These modeling difficulties are discussed and dynamic fault tree modeling techniques for handling them are described and demonstrated. Several advanced fault tolerant computer systems are described, and fault tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that is capable of solving the fault tree models presented

HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 2: HARP tutorial

The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. The Hybrid Automated Reliability Predictor (HARP) tutorial provides insight into HARP modeling techniques and the interactive textual prompting input language via a step-by-step explanation and demonstration of HARP's fault occurrence/repair model and the fault/error handling models. Example applications are worked in their entirety and the HARP tabular output data are presented for each. Simple models are presented at first with each succeeding example demonstrating greater modeling power and complexity. This document is not intended to present the theoretical and mathematical basis for HARP

HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 1: HARP introduction and user's guide

The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed to be compatible with most computing platforms and operating systems, and some programs have been beta tested, within the aerospace community for over 8 years. Volume 1 provides an introduction to the HARP program. Comprehensive information on HARP mathematical models can be found in the references

Developing a low-cost, high-quality software tool for dynamic fault tree analysis

Abstract—Sophisticated modeling and analysis methods are being developed in academic and industrial research labs for reliability engineering and other domains. The evaluation and evolution of such methods based on use in practice is critical to research progress, but few such methods see widespread use. A critical impediment to disseminating new methods is the inability to produce, at a reasonable cost, supporting software tools that have the • usability and dependability characteristics that industrial users require, • evolvability to accommodate software change as the underlying analysis methods are refined AND enhanced. The difficulty of software development thus emerges as a key impediment to advances in engineering modeling and analysis. Today, producing sophisticated software tools is costly and difficult, even for capable software developers. One problem is that when common design-methods, such as object-oriented programming, are used to build such tools, the results are often large, complex, and thus costly programs. Tools on the order of a million lines of code are typical, with much of the code devoted to • tool interoperability, • human-computer interface, • other issues not directly related to modeling and analysis. Making matters worse, domain experts, such as reliability engineering researchers, often lack skills in modern software development, while software engineers and researchers lack knowledge of the application domains. All too often the results of tool-development efforts today are thus • costly, • hard to use, • not dependable, • essentially unmaintainable. This paper presents an approach to tool development that attacks these problems. Progress requires synergistic, interdisciplinary collaborations between application-domain and software-engineering researchers. We have pursued such an approach in developing Galileo: a fault tree modeling and analysis tool. These innovations are described in 2 dimensions 1) The Galileo core reliability modeling and analysis function. 2) Our work on software engineering for high-quality, low-cost modeling and analysis tools