Uninterruptible Power Supply
An uninterruptible power supply (UPS) is a battery backup system that supplies power to the network server in the event of an electrical power outage. The UPS is not designed to keep the network server running for long periods of time. It is designed to supply power to the network server just long enough for the network server to be shut down gracefully. The shutdown process is usually done by software running on the network server that is monitoring the UPS by means of a serial cable running from the network server to the UPS. A UPS also conditions the power (eliminates spikes and sags) before it gets to the network server. If a network server has multiple power supplies, each of them should be connected to a different UPS to provide the ultimate in power protection and network server reliability.