A power distribution unit is a device for controlling electrical power in a data center.
The most basic PDU is a large power strip without surge protection. It is designed to provide standard electrical outlets for data center equipment and has no monitoring or remote access capabilities. The floor-mounted and rack-mounted PDUs can be more sophisticated, providing data that can be used for power usage effectiveness (PUE) calculations.
A floor-mounted PDU, sometimes called a main distribution unit (MDU), provides an important management bridge between a building's primary power and various equipment racks within a data center or network operations center (NOC). Each PDU can handle larger amounts of energy than an ordinary power strip (300 kilovolt-amps and higher depending on the manufacturer and model) and typically provides power to multiple equipment racks.
A rack-mountable PDU mounts directly to an equipment rack so it can control and monitor power to specific servers, switches and other data center devices and assist in balancing power loads. Rack-mountable PDAs are known by several different names, including smart PDUs and intelligent PDUs. Such PDUs include three-phase displays for devices sharing power well as remote management tools that use the Simple Network Management Protocol (SNMP) to provide administrators with the ability to adjust and monitor power demands from offsite locations.