Fault Tolerance Distributed

Fault Tolerance Distributed

ITV Model-based Analysis and Design of Embedded SoftwareTechniques and methods for Critical Software

Anders P. RavnAalborg University

August 2011

FT basis: Redundancy

• Time

• Space

Try Retry Retry ...

TryTryTry

...

BW p. 109

Fault Tolerance

Basic Strategies

Example

Fault Hypotheses

Fault-Tolerant System

Impulse Generator

CU

Voter and Arbiter

Parameters

Properties

Procedure1. Model the correct component and check that it

has the desired properties.2. Model relevant faults and introduce them as

internal transitions to error states. Check that this is fault-affected.

3. Introduce into the model the mechanisms for fault detection, error recovery and masking and check that the desired properties are valid for this design.