Maintainability

A maintainable system is easier to operate, understand, and change. This lesson separates those everyday engineering concerns from the narrower question of how quickly a failed component can be restored.

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

In repair-time analysis, maintainability (M) is the probability of restoring the required functions within a specified time under stated repair conditions. For example, a hypothetical maintainability value of 95% at 30 minutes means a 0.95 probability of restoration within that interval. This is narrower than the codebase and operational qualities described above.