System failures and errors Flashcards
(9 cards)
1
Q
What are the different levels of failure?
A
- Regulatory failure
- Managerial failure
- Hardware failure
- Software failure
- Human failure
2
Q
Why are complex systems prone to large failures?
A
A failure in one part may cause a sequence of failures to occur
3
Q
What is a complex system?
A
Several parts working together to give a singular output, that cannot be predicted from the behaviour of a single part
4
Q
What is dependability?
A
When a computer system can be trusted to deliver a service
5
Q
What are the 3 components of Laprie’s model?
A
- Impairments
- Means
- Attributes
6
Q
what are the impairments in Laprie’s model?
A
- System failure: service is not delivered as expected
- System error: system doesn’t follow its specification
- System fault: incorrect system state
- Human error
7
Q
What are the means in Laprie’s model?
A
- Fault avoidance
- Fault tolerance
- Fault removal: reducing number of/severity of faults
- Fault forecasting: estimating number of faults
8
Q
What are the primary attributes of dependability in Laprie’s model?
A
- Availability: system can deliver services when requested
- Reliability: deliver services as specified
- Safety: no failures
- Security
9
Q
What are the secondary attributes of dependability in Laprie’s model?
A
- Timelessness: responding quickly
- Survivability
- Recoverability: can recover from errors
- Maintainability
