Many of our machines come with the option of having a second power supply, but the purpose of this second supply is not to supply additional power. Its purpose is to provide power in the event the first supply stops working. This option is usually called “redundant power.”

 

The way this works is that under normal conditions, the power load is roughly balanced between the two supplies. This ensures that both power supplies are working, warmed up, and ready. Ready for what? Ready for one of them to malfunction and stop supplying power, or for the power input to a power supply to fail. If that happens, the second power supply immediately picks up the full load, and the server will continue functioning as before. The only difference is that the server will enter an alert mode that it has lost power supply redundancy, so the failed supply can be replaced.

 

Most of the servers well sell can have a failed power supply replaced without having to be powered down, that way the users never experience an interruption in service.