Reliability and Safety

1
Reliability and Safety

• What can go wrong?

2
Risks of Computing

• They support many aspects of our security
• Fly by wire aircraft
• Patient monitoring and care administration
• Financial transactions
• Telephone networks
• Military surveillance and responses

3
Three Categories of Failures

• Problems for individuals
• System failures that affect large numbers of
  people or cost large amounts of money
• Problems in safety-critical applications

4
Problems for Individuals

• Billing Errors
• Not enough care - input error
• Not enough testing - reasonable range
• Not enough training

5
Database Accuracy Problems

• Info in database is not accurate
• Automatic entering of info - mistakes can be
  overlooked
• Erroneous duplication - copies of incorrect info
  can be in other systems
• Insufficient training - not knowledgeable enough
  about the system

6
Possible States of a Computer

• Functioning correctly
• Functioning incorrectly
• Down
• Intentionally off

7
Causes of Computer Failure

• Faulty design of software or hardware
• Sloppy implementation
• Careless or insufficiently trained users
• Poor user interfaces
• Hardware/Software malfunctions
• Specification errors
• Scope/Application inconsistency

8
Computer Users Perspective

• Should user should understand
• limitations of the computers
• the need for proper training
• the need for responsible use
• the difference between good products and bad ones

9
Computer Professional Perspective

• The professional should
• study computer failures
• study computer ethics

10
Educated Member of Society Perspective

• Education will
• help us evaluate the reliability and safety of
  various computer applications
• help evaluate computer technology

11
Relevant Research Topics

• Architecture hardware and software
• Systems engineering
• Reasoning languages, techniques and engineering
• Requirements analysis
• Fault tolerance
• Repair and maintenance
• Holistic safety arguments
• Formal methods
• Real-time issues

12
Consumer Hardware and Software

• Usually have more serious errors in their first
  releases
• Regularly sold with known bugs
• Hardware also has flaws
• Tradeoff between cost, debugging, and marketing
• Dishonesty, denials of problems, lack of adequate
  response to complaints