Hardware Today — UPSes Heed the Call for Backup

Monday Jul 26th 2004 by Ben Freeman
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An uninterruptible power supply is a must-have for organizations of all sizes. This week, Hardware Today discusses what to look for in a UPS and offers a jumpstart on comparison shopping with the spotlight turned on APC and MGE UPS Systems.

These days, the need for backup power is a pretty easy sell. Organizational concerns about power outages and terrorism help fuel the need to ensure the juice is always on tap so systems can continue running. This week, Hardware Today surveys the always-on world of backup power in our monthly server room components feature. We'll discuss what to look for as well as jumpstart your comparison shopping by spotlighting two vendors: market standout American Power Conversion (APC) and France-based MGE UPS Systems.

Uninterruptible Power, Somewhat

UPS: A power supply that includes a battery to maintain power in the event of a power outage. In an outage, a UPS keeps the server powered on long enough for the admin to take corrective action.

In an outage, an uninterruptible power supply (UPS) uses batteries to keep the server powered on long enough for an administrator to take corrective action. A UPS works in conjunction with a backup generator, or backs up critical data and shuts down before the server loses power altogether. Any UPS worth its salt can issue server commands to send out alerts.

Three kinds of UPSes proliferate.

  • Standby power systems (SPSes) use a power inverter, which kicks in to convert DC battery current to AC when the UPS detects a problem with normal outlet power. The switchover from AC to battery, however, leaves a several-millisecond-long gap in server power.
  • Line-interactive UPSes use a flexible inverter/converter unit that charges the battery when the power is on, then converts battery power into AC in case of an outage. This results in a time gap slightly smaller than that of SPSes during switchover.
  • Only online UPSes, the most expensive option, provide truly uninterrupted power. Online UPSes power the server entirely from the battery. Under ordinary circumstances, incoming AC power charges the battery. If power cuts out, the battery simply ceases charging, and the server doesn't know the difference — so long as the battery still contains juice.

APC Product Line Manager Brian Standley downplays the 2 millisecond to 4 millisecond switchover lag inherent to SPSes and line-interactive UPSes, noting, "Reality is, IT equipment utilizes switch mode power supplies that have built-in capacitance to handle upwards of 40-80 millisecond losses of power." He adds, "even with a standby UPS, you will not see interrupted power."

MGE UPS Systems Director of Marketing Jack Pouchet takes a more conservative line, "Cheaper standby UPS systems [provide] basic backup for less-sensitive and less-critical desktop PCs and peripherals," he said, "but are not recommended for protecting core servers or essential storage and connectivity devices."

Bottom line: If you can afford it, use an online UPS; if you can't, take comfort in the fact that servers typically stay powered through brief millisecond gaps in power. Just make sure to test your batteries regularly, as otherwise you won't know they're dead until the power spikes and slams your server.

For New Buyers

Pouchet steers first-time buyers toward an online UPS, where always-deployed batteries provide regulated "digital quality power." Look for hot swappable batteries and the option to upgrade them. In addition, automatic cutover to a redundant power source can be useful for a malfunction, and server communications capabilities are essential.

It is also important that the vendor has factory servicing for its UPSes. "While third-party computer repair options are abundant, the same cannot be said for UPS service," Pouchet said. "Some vendors that specialize in smaller products rely on third-party or depot repair options that can leave the user without power protection for extended periods."

Standley adds that management software should "provide event notification and logging," as well as "automatic, graceful server shutdown in the event of an extended power failure."

>> Solutions for SMBs and Enterprises

SMB-Tailored Solutions

"APC UPSes are known for their rock-solid reliability," Standley said.

APC positions its Smart-UPS line toward the entry server space with line-interactive rack or tower UPSes priced from $200 to $3,000, depending on battery runtime. APC also offers an Online Smart-UPS RT line, with products priced from $2,000 to $7,000.

APC's Symmetra models provide dual-battery redundancy in a single chassis. They are priced from $3,000 to $12,000. "Symmetra UPSes offer N+1 redundancy to maximize network reliability and scalable power capacity to allow a 'Pay as you grow' approach," Standley said.

Software solutions like PowerChute, UPS Network Management Cards, and InfraStruXure Manager further illustrate the breadth of APC's offerings.

MGE gears its online Pulsar EX and Pulsar EX RT UPSes at low-end and midrange servers, respectively. Though MGE doesn't publish exact prices, we found price estimates from around $500 for the Pulsar EX to $1,500 for the EX RT.

Pouchet recommends the Pulsar EX RT for mission-critical or telecom servers. "Pulsar EX RT models are true online UPSes incorporating Digital Quality Power that provides the highest level of power protection with the cleanest waveform and no switching time during power disturbances," he said.

Enterprise-Class Solutions

APC's high voltage small-footprint Symmetra PX provides 10kW to 80kW of redundant power, while the gigantic Symmetra MW models provide a whopping 400kW to 1.6mW. APC also offers on-demand InfraStruXure solutions.

"InfraStruXure integrates power, racks, cooling, and management into a single architecture of standardized pre-engineered components designed to work together seamlessly," Standley said.

MGE recommends its EPS6000 and Galaxy UPSes as "very robust centralized three-phase online UPS systems" that provide up to 800kVA for enterprises.

Pouchet steers customers away from less-efficient "distributed power installations" for enterprisewide deployments. He recommends users "right size" with a large centralized UPS to accommodate planned growth. "While the initial cost might be slightly higher, the cost per kVA after even a modest upgrade quickly proves to be significantly lower," he said, "while the user has the benefit of a much more robust system, reduced operating costs, minimum impact on the computer room, and simplified management from the beginning."

The Best Laid Plans

Ultimately, more important than the actual product is the plan driving it. Even the most complex UPS product can be foiled, and sometimes by a far smaller factor than a natural disaster or terrorist act. Robert Frances Group Principal Analyst Ed Broderick cited an example of problem that once befell a $100 million American Airlines SABRE data center. The server room was filled with the latest and greatest technology on the market, including dual power sources and multiple UPSes, multiple turbine, multiple generators, and "everything backed up 18 ways to Sunday," Broderick noted.

However, "What they forgot to measure," Broderick said, "was the wingspan of a stupid animal." Unfortunately, "both power supplies came together as they entered the data center building — 18 inches apart." This attracted the curiosity of a soon-to-be-crispy 24-inch-wide mammal. "He sat on the power lines and shorted them both out, and they were down for 20 hours. 100 million bucks went up for naught," Broderick said.

The problem, Broderick surmised, was that one less of everything that was needed from the available backup pool actually kicked in.

The moral? Make sure you plan for everything, otherwise, it's "100 million bucks up in flames, for a moose or a rodent."

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