The majority of the servers that TechMikeNY sells are dual power supply unit servers, or, in other words, come with two power supplies. For the budget conscious, we do provide some configurations with one power supply and the option to add a second power supply. The plain and simple reason for this is redundancy. If one PSU should fail, the other unit will take over since both units are capable of handling the full wattage needed to run the server. For example, if your server pulls 500W total and there are two 750W power supplies installed, if one PSU fails, the other 750W power supply will provide enough power to keep the server running. Additionally, for servers in large data centers, each PSU can be put on a separate circuit – so should one circuit fail, the redundant PSU on the second circuit will take up the full load.
What Is the Advantage of Having Dual Power Supply Units and Will It Cause My Server to Draw More Power?
Under normal loads, with two PSU’s in redundancy mode, the PSU’s will split the load 50/50. As such, the dual power supply server will not pull more power or add to your electricity bill with dual PSU’s installed. As an added safeguard, HP and Dell servers will show errors during boot if the power required exceeds the output of the power supply. Additionally, most PSU’s are hot-swappable – meaning in the event of a failure of one of the units, you can swap out a replacement unit with no downtime to the server.
Bottom line: a redundant or secondary PSU is not required for your server to run, but highly recommended to avoid the system crashing due to an electrical or PSU failure. For mission-critical servers, it is considered an essential set-up for system stability.