10. Redundancy

Redundancy means designing systems with duplicate components so that if one component fails, another can continue supporting operations.

In a data center, redundancy should be planned through risk assessment, including whether separate utility entrances or communication paths are needed.

For full redundancy, devices may use dual power supplies connected to different power sources. Those sources can also be backed up by batteries and generators.

In high-availability environments, even the generators may be redundant.

Main Idea
Redundancy keeps systems available by using backup components and backup paths.