What are Fault-Tolerant Systems?
Fault-tolerant systems refer to systems designed with the capability to continue operating and providing correct outputs even in the presence of faults or errors. The fundamental approach to achieving fault tolerance is through redundancy, which involves incorporating multiple copies (redundant components) of essential elements within the system. Redundancy allows the system to mask errors by comparing the outputs of redundant components and ensuring correct operation even if one of the components fails.
Here are key points related to fault-tolerant systems
- Redundancy: The use of two or more identical copies of processing elements (PEs) within the system. Redundancy is a central concept in fault-tolerant design.
- Redundancy Schemes: Different redundancy schemes are employed to achieve fault tolerance. The paragraph hints at describing some popular redundancy schemes in subsequent sections.
- Masking Redundancy: Also referred to as “masking redundancy,” this technique involves using extra PEs in the system to instantly mask the effects of a faulty component.
- Duplex System: A specific form of redundancy where two identical copies (duplex) of the system are used. Detecting and correcting faults in a duplex system often requires additional fault detection mechanisms.
- Triple Modular Redundancy (TMR): A form of redundancy where three identical copies of components are used. In the context of the paragraph, a TMR system involves three redundant PEs.
- Fault Detection: Even in redundant systems, detecting faulty components is crucial. In the example given, if one PE produces an output of 1 and another produces 0, additional fault detection is needed to determine the correct output.
- Illustration of TMR System: The paragraph mentions that a TMR system is illustrated indicating a visual representation of a system employing triple modular redundancy.
Overall, fault-tolerant systems aim to provide reliable and continuous operation, and redundancy is a key strategy to achieve this goal. Different redundancy schemes offer varying levels of fault tolerance, and the choice depends on the specific requirements and characteristics of the system.
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