Reliability-related requirements in software-intensive systems

System-level reliability and availability requirements set forth by U.S. Government agencies procuring large software-intensive systems encompass both hardware and software. However, specifications, statement of work requirements, and compliance documents (standards) usually implicitly or explicitly focus on hardware and are largely silent about software reliability, maintainability, availability and dependability. Consequently, contractor system reliability analyses and design reviews usually ignore quantitative software reliability, maintainability, availability, and dependability requirements. During system testing and evaluation, data on software operating times, failure rates, and recovery times are not collected. Finally, logistics and support specialists devote significant attention to sparing and maintenance concept development, but often do not adequately consider the software-related sustainment issues of large computer systems. These problems can be solved by appropriate definition of requirements for software-intensive system reliability in specifications and in the definition of programmatic requirements in contractual documentation.