What type of power supply redundancy is often recommended for critical servers?

Dual power supply redundancy is a widely recommended approach for critical servers because it enhances the reliability and availability of the server's power. In this configuration, two power supplies are installed in the server, each connected to different power sources. This design ensures that if one power supply fails or if there is an issue with one power source, the other can continue to provide power, thus minimizing the risk of downtime.

This setup is particularly essential in environments where continuous operation is crucial, as it allows for maintenance or replacement of one power supply without interrupting service. The redundancy of power supplies aligns with best practices for high-availability systems, providing an extra layer of security against power-related failures.

The other options, while they serve specific purposes, do not provide the same level of immediate redundancy as dual power supplies in a server context. A single power supply lacks redundancy altogether, and while a UPS provides backup power during outages, it does not directly address power supply failures within the server itself. A dedicated generator is a solution for larger power outages but is not a practical method for immediate and seamless failover in the context of an individual server's power needs.