Maintainability

Define maintainability as the system’s ability to be easily operated, understood, and modified. Explore how engineers measure this crucial non-functional requirement using the MTTR metric. Understand the relationship between maintainability and reliability for achieving high availability in System Design.

What is maintainability?

After building a system, engineers must keep it operational. This involves fixing bugs, adding features, updating platforms, and ensuring smooth operations. Maintainability measures how easily a system supports these tasks. We can divide maintainability into three aspects:

  1. Operability: The ease of ensuring smooth operations and recovering from faults.

  2. Lucidity: The simplicity of the codebase. A simpler codebase is easier to understand and maintain.

  3. Modifiability: The ability to integrate changes and new features without difficulty.

Measuring maintainability

Maintainability (M) is the probability that a service will restore its functions within a specified time after a fault. It measures how quickly the service returns to normal operating conditions. For example, if a component has a maintainability value of 95% for 30 minutes, the probability of restoring the component within that time is 0.95.