Uninterruptible Power Supply

Uninterruptible Power Supply

An Uninterruptible Power Supply (UPS) is a special battery (or sometimes a generator) that supplies power to an electronic device in the event of a power failure. UPSs commonly are used with network servers to prevent a disorderly shutdown by warning users to log out. After a predetermined waiting period, the UPS software performs an orderly shutdown of the server. Many UPS units also regulate power distribution and serve as protection against power surges. Remember that a UPS generally does not provide for continued network functionality for longer than a few minutes. A UPS is not intended to keep the server running through a long power outage, but rather is designed to give the server time to do what it needs to before shutting down. This can prevent the data loss and system corruption that sometimes results from sudden shutdown.

When purchasing a UPS for a server, note that these come in many varieties (see Figure 9.2). As noted earlier, the UPS is really just a battery backup. Just like a car battery, the more powerful it is, the more expensive it is. Prices run from the hundreds to many thousands of dollars. Before you buy, know how many servers you will be running off the UPS and how much time they need to shutdown properly. One of the most popular UPS manufacturers is APC (American Power Conversion), a company that offers a full line of power supply and UPS products.

Backups mainly provide a quick method for system recovery. They require a long and tedious restoration process that can cost your company dearly in lost revenue and productivity. Because of this, the following sections examine some methods of minimizing—or even preventing—downtime in case of a drive failure.