What do you consider a serious threat to your technology systems and business data? Hackers? Terrorists? Competitors? An incompetent employee? A spilled cup of coffee? In reality, one of the most com- mon threats--and the easiest to prevent--is a momentary interruption in power, which can crash systems, destroy crucial data, and cost a lot of time and money.

Uninterruptible power supply systems have been protecting IT systems for many years. Given the millions of dollars that large companies spend on computer security, there's no good excuse for not protecting systems from power problems. Businesses are expected to spend about $2 billion this year on UPS systems that vendors keep improving with new technology, longer power reserves, and lower costs.

Most power blips or outages last less than a minute but can cost a company days of data if computers aren't protected by a UPS. At their most basic, UPS systems aren't complicated. The heart of most systems are batteries that keep computer and storage systems running for as long as four hours, depending on the load. Some companies use flywheel systems, which store kinetic energy that can be used to generate electricity in an emergency, to provide power for short durations instead of battery-based UPS systems. Flywheel systems are often used to provide just enough power to allow on-site backup generators to get online.

	UPS systems are needed because a power brownout could cause AOL to lose days of crucial data in its hundreds of servers, senior network engineer Chase says.

Internet service provider America Online has turned to UPS systems to avoid power problems. "To go without would be terrible because any brownout could force us to throw out days of data," says Jeff Chase, senior network engineer at AOL.

AOL gets up to 15 minutes of backup time from American Power Conversion Corp. UPS racks. The APC PowerStruXure system, now called InfraStruXure, replaced an older APC product that required a smaller UPS attached to each server rack in the data center. With more than 200 servers, the older system caused some problems. "With so many of them, the UPSes caused harmonic frequency over the network, or dirty power," Chase says. "We weren't clear if it was affecting our outside lines."

To help solve AOL's problem, APC developed a set of two racks that can service any part of the data center. Chase just plugs them into the network as needed. "The PowerStruXure is a scalable, portable system that we can add more batteries to if we need more run time," he says. "And the power consumption of the racks is much less than the others in the data center."

Chase says his UPS systems are easy to use and manage. "They're user-maintainable, and I can pop one out and pop in a new one," he says. "Other UPS systems are as big as a deep freezer and require a service contract."