Fault Tolerance Requirements
The basic characteristics of fault tolerance require:
- No single point of failure
- Fault isolation to the failing component
- Fault containment to prevent propagation of the failure
- Availability of reversion modes
In addition, fault tolerant systems are characterized in terms of both planned service outages and unplanned service outages. These are usually measured at the application level and not just at a hardware level. The figure of merit is called availability and is expressed as a percentage. For example, a five nines system would statistically provide 99.999% availability.
Fault-tolerant systems are typically based on the concept of redundancy.
Read more about this topic: Fault-tolerant System
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