If the electrical power to your office hiccups for even a fraction of a second, your lights, coffeemaker and air conditioning probably won't even notice ... but your computers and network equipment will. And if the power stays off — for hours, minutes or even seconds — your servers, network routers, desktop computers and other gear may lose important data or suffer software corruption, if you haven't invested in one or more uninterruptible power supplies (UPSs).
As you may know, UPSs are designed to provide backup power to electronic equipment in the event of a temporary electrical outage. They fall into three main categories in roughly ascending order of price and performance.
1. A standby, or off-line, UPS is the simplest. When it detects a drop (or a spike) in the electric power coming from the wall outlet, it switches over to its internal battery to power the connected equipment. There's a slight lag in the switchover, but typically not long enough to cause a shutdown or data loss.
2. A line-interactive UPS adds a trans.former that can boost or moderate the incoming voltage to the right level without having to switch over to battery power.
3. An online UPS powers the connected equipment from the internal battery all the time and uses the incoming AC voltage to keep the battery charged. In the event of a power outage, there's no drop in voltage or switchover to the battery. The only change in state is that the battery starts to drain once recharging stops. Most online UPSs are "dual conversion" — the AC from the wall is converted to DC for charging the battery, and then back again to AC to power the equipment. Some newer models may be "triple-conversion," converting the DC power that goes to the battery to a different DC voltage, which can extend the life of the battery perhaps another year. Because of the constant use, the battery in an online UPS typically needs to be replaced every three to five years.
Of course, though UPSs can provide up to several hours of battery backup, they are not designed to keep a business fully operational during a prolonged power failure. That usually requires a backup generator. The role of a UPS is to protect equipment from brief outages or spikes (most include surge suppressors) and, in the case of an extended power failure, provide sufficient time to complete tasks in progress and properly shut down systems to prevent data loss or corruption.
Choosing among the different UPS types depends on the power requirements and critical nature of the equipment being protected. Prices span the entire spectrum from less than $100 for a basic standby UPS to protect one or two devices to thousands of dollars for high-capacity line-interactive and online models designed to protect a rack's worth of equipment. Ultra high-end models that protect an entire server room or data center can cost tens of thousands of dollars.
A standby UPS will usually suffice for most desktop computers, printers and other noncritical peripherals, while environments that suffer frequent power dips and surges or are subject to electrical interference or line "noise" from other equipment will benefit from a line-interactive model. An online UPS is a sensible investment to protect a telephone system and other gear that a business relies on for mission-critical operations, such as transaction processing, Internet access or e-mail.
"Virtually all our computers are on UPSs," reports Dan Bent, director of claims technology at The Nyhart Company, an Indianapolis-based benefits administration company with about 80 employees. About a dozen servers, including an HP 9000 that is "business critical," plus a firewall, a Web server, a storage-area network, an e-mail server, several network switches and hubs, four Citrix servers and the company's phone system are protected by three online UPSs and one line-interactive unit in its server room. The firm uses standby units from APC to protect all its desktops, Bent adds.
Not every piece of equipment needs its own UPS, and it's often economical to consolidate protection using one or two larger models with a lot of high-end features, rather than individual UPSs for each device.
Lebanon Internal Medicine Associates (LIMA), a multi-specialty internal medicine group in Lebanon, Pa., recently moved from individual UPSs to an APC Symmetra LX dual-conversion online UPS to protect all the servers and equipment in its telecom room. The UPS provides backup power for the company's main Windows server, an Exchange server, a digital dictation system, a Windows-based server that runs its laboratory information system and a Linux-based practice-management server, according to Tim Jesiolowski, LIMA's IT coordinator. Network gear connected through the APC UPS includes a Cisco router/gateway, SonicWALL firewall, and NetGear and SMC switches.
"If we do have a power outage, which in the past has been typically 15 to 20 minutes, it leaves me enough time to do an orderly shutdown," Jesiolowski says. "I'd much rather have the end users inconvenienced by having to reconnect to the server when it comes back up than take the time to rebuild a corrupted database caused by an improper shutdown."