Single Point of Failure

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A router, as a single point of failure for the communication network between computers

A Single Point of Failure, (SPOF), is a part of a system which, if it fails, will stop the entire system from working ^[1]. They are undesirable in any system whose goal is high availability, be it a network, software application or other industrial system.

The assessment of a potentially single location of failure identifies the critical components of a complex system that would provoke a total systems failure in case of malfunction. Highly reliable systems may not rely on any such individual component.

The strategy to prevent total system failure is

Reduced Complexity

Complex systems shall be designed according to principles decomposing complexity to the required level.

Redundancy

Redundant systems include a double instance for any critical component with an automatic and robust switch or handle to turn control over to the other well functioning unit (failover)

Diversity

Diversity design is a special redundancy concept that cares for the doubling of functionality in completely different design setups of components to decrease the probability that redundant components might fail both at the same time under identical conditions.

Transparency

Whatever systems design will deliver, long term reliability is based on transparent and comprehensive documentation.

See also

• Human reliability
• Safety engineering
• Reliability engineering
• Reliability theory
• Reliable systems design
• Reliability modelling
• Single Point of Truth

Notes