Redundancy Optimization: Series vs. Parallel Modeling
Quantifying Uptime Gains through Architectural Configuration
In critical infrastructure design, system reliability is determined not just by the quality of individual components, but by their topological arrangement. Engineering systems typically fall into two primary configurations: Series and Parallel.
Series Systems
A chain where every link must hold. The failure of any single component results in system failure. This configuration is mathematically defined as the product of all component reliabilities:
Parallel Systems
A redundant setup where the system survives as long as at least one path remains active. Reliability is calculated by subtracting the probability of all paths failing from unity:
Interactive Redundancy Simulator
Use the tool below to model your system. Add components, set their individual reliability ratings (probability of success), and toggle between Series and Parallel modes to observe the impact on total system availability.
Configuration
Parallel redundancy means the system survives if AT LEAST ONE component works.
Series Formula
System reliability is ALWAYS lower than the reliability of the weakest component. A single point of failure (SPOF) dictates the entire chain.
Parallel Formula
Redundancy significantly increases uptime. Even with mediocre 90% components, dual-parallel configuration yields 99% reliability.
The "Weak Link" Principle
In a series configuration (e.g., a power cable connected to a switch), the system reliability is always lower than the reliability of its weakest component. For example, a 99.9% reliable switch connected to a 95% reliable power source results in a system that is only 94.9% reliable.
Conversely, in a parallel configuration (e.g., dual redundant power supplies), the system reliability is higher than any single component. Two 95% reliable power supplies in parallel yield a system reliability of 99.75%.