Chapter 10: Dependable Systems Flashcards
What is dependability?
Dependability reflects a system’s trustworthiness and the degree of user confidence, covering attributes like availability, reliability, safety, security, and resilience
Define availability
Availability is the probability that a system will be operational and able to deliver requested services at any point in time
Explain reliability
Explain reliabilityReliability is the probability of failure-free operation over a specified time, in a given environment, for a specific purpose
What is safety in terms of dependability?
Safety is a judgment of how likely it is that the system will cause damage to people or its environment
Define security in dependability
Security is the system’s ability to protect itself against deliberate or accidental intrusion
Explain resilience
Resilience is the ability of the system to resist and recover from damaging events
What are sociotechnical systems?
Sociotechnical systems involve software, hardware, and human operators as interdependent components, operating with a social or organizational purpose in a complex and changing environment
What challenges do sociotechnical systems pose for dependability engineering?
Challenges include complexity, diversity, uncertainty, emergence, and evolution
How can sociotechnical systems be modeled?
Sociotechnical systems can be modeled using various techniques, such as system diagrams, context models, interaction models, or structural models
What are some techniques for analyzing sociotechnical systems?
Techniques include hazard analysis, risk analysis, fault tree analysis, and event tree analysis
Define critical systems
Critical systems are systems whose failure may result in injury, environmental damage, or extensive economic losses. They can be safety-critical, mission-critical, or business-critical
What is critical systems engineering?
Critical systems engineering involves activities such as requirements engineering, design engineering, verification and validation, configuration management, and quality management to develop dependable critical systems
Name some methods for ensuring dependability in critical systems
Methods include formal methods, fault tolerance techniques, diversity techniques, and process improvement techniques
Why are dependable systems important?
Dependable systems are crucial because they impact the well-being, safety, and welfare of individuals and society
How do dependable systems prevent or minimize losses and damages?
They can prevent or minimize the losses or damages caused by system failures or malicious attacks
What are the main activities in developing dependable systems?
Developing dependable systems involves activities such as considering sociotechnical systems, introducing redundancy and diversity, applying dependable processes, and using formal methods
What factors influence dependability requirements?
Factors include the type and criticality of the system, the costs and benefits of dependability, and the expectations and needs of the stakeholders
How can redundancy and diversity be achieved in systems?
Techniques include hardware redundancy, software redundancy, information redundancy, time redundancy, physical diversity, and logical diversity
What are the advantages of using formal methods in system development?
Formal methods can improve system quality and dependability, support reuse and maintenance, and facilitate communication among stakeholders
What are the disadvantages of using formal methods?
What does dependability encompass in system attributes?
Dependability encompasses reliability, availability, safety, security, and maintainability
What is the role of redundancy in dependability?
Redundancy involves introducing extra components or variants to cope with failures or attacks
Explain how formal methods contribute to system development
Formal methods use rigorous mathematical techniques to specify, design, verify, and validate the system
What challenges do sociotechnical systems pose for dependability engineering?
Sociotechnical systems challenge dependability engineering with complexity, diversity, uncertainty, emergence, and evolution
Define availability in terms of dependability
Availability is the probability that a system will be operational and able to deliver the requested services at any point in time
What is the primary goal of critical systems engineering?
The primary goal of critical systems engineering is to develop dependable critical systems that meet their requirements and standards
What is the difference between safety-critical and business-critical systems?
Safety-critical systems involve the potential for harm to people or the environment, while business-critical systems are essential for an organization’s core operations
What are some techniques for achieving redundancy in systems?
Techniques for achieving redundancy include hardware redundancy, software redundancy, information redundancy, time redundancy, physical diversity, and logical diversity
How does redundancy contribute to dependability?
Redundancy provides backup or alternative functionality to cope with system failures or attacks, enhancing dependability
What role do sociotechnical systems play in system development?
Sociotechnical systems consider interactions and dependencies between the software system and its social and organizational environment, recognizing their impact on dependability
