Definition
A single point of failure is a component, path, or function within a system whose failure alone (without any other simultaneous failure) is sufficient to cause the entire system to fail, because no redundant alternative exists. Identifying single points of failure is a core step in deciding where redundancy is actually needed.
Key facts
- Defined by sufficiency: its failure alone is enough to cause overall system failure, no combination with another failure is needed.
- The absence of redundancy is what creates a single point of failure; adding a backup path is the direct way to eliminate one.
- Identifying single points of failure is typically done through system-level analysis such as Fault Tree Analysis or RCM.
- Not every single point of failure justifies the cost of redundancy: the decision depends on the consequence if that point fails.
What does Single point of failure reveal about failures?
A single point of failure identifies a specific component or path in a system architecture that, if it fails, brings down the entire system on its own, with no alternative path or backup component available to maintain function.
How do teams use Single point of failure in failure analysis?
Redundancy is the deliberate design response to a single point of failure: adding a backup path so no single component's failure alone can bring down the system. A common cause failure is the risk that even a redundant design can fail as if it had a single point of failure, if both the primary and backup paths share an unrecognized common vulnerability.
FAQ
Frequently asked questions
Which individual weakness can cause the overall function to fail?
A single point of failure: a component or path whose failure alone, with no backup available, is sufficient to bring down the entire system.
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