120 likes | 296 Views
Software Fault Tolerance – The big Picture. mMIC-SFT September 2003 Anders P. Ravn Aalborg University. Fault Tolerance. Means to isolate component faults. Prevents system failures. May increase system dependability. Dependability - attributes. Availability Reliability Safety
E N D
Software Fault Tolerance –The big Picture mMIC-SFT September 2003 Anders P. Ravn Aalborg University
Fault Tolerance Means to isolate componentfaults Prevents systemfailures May increase systemdependability
Dependability - attributes • Availability • Reliability • Safety • Confidentiality • Integrity • Maintainability BW p. 139
Dependability - means • Fault prevention • Fault tolerance • Error Removal • Failure Forecasting BW p. 106, ...
... Fault Error Failure Fault Dependability - impediments • Faults • Errors • Failures BW p. 103, ...
byzantine Fault classification • physical (internal/external) • logical (design/interaction) • Origin • Kind • Property • omission • value • timing • duration (permanent, transient) • consistency (determinate, nondeterminate) • autonomy (spontaneous, event-dependent)
Error Classification • (Fault Error) • Effect • Extent • latent • effective • local • distributed
Failure Classification • (Fault Failure) • Consequence • benign • malign (a mishap) BW (Failure modes) p. 105
Fault Avoidance • process (procedures) • notations • tools • Careful Design • Conservative Design • robust functionality • testability • tracability
Error Removal • Verification (analysis of design) • Test (analysis of implementation)
Failure Forecasting • Calculation – analysis of design • Simulation – measurement on design • Test -- measurement on implementation