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General Information
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June 19, 2009
• Vol.31 Issue 17
Page(s) 30 in print issue
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Ensure Your Equipment Is Getting High-Quality Power
Tips For Managing Data Center Power Issues
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| Key Points
• As data center managers make changes to increase power efficiency, they must also assess how the changes affect power quality.
• Monitoring power usage is critical in today’s data centers due to dynamic loads and increasing equipment density.
• Power-quality problems are often caused by human error. Simplifying and modularizing systems makes power easier to manage and reduces the risk of outages. | Data centers obviously need quality power coming from the utility company with the least risk of service disruptions. Locating facilities in an area with underground power lines, little or no surrounding construction, and transformers or substations with failover capabilities helps reduce power-quality problems.
Even so, data center facilities are still subject to power-quality disturbances such as sags, surges, and harmonics. How can data center managers ensure equipment is getting high-quality power inside the facility? UPSes have solved many power conditioning problems, but today’s data centers are faced with new challenges that can affect power quality.
 Current Power-Quality Issues
Changes to a data center’s power load, rack density, and efficiency present challenges for managing power quality. Years ago, for example, servers operated at a consistent load level. Current servers have a dynamic power-usage profile that fluctuates based on demand. Although power-saving techniques reduce energy costs, they also create less-predictable power requirements and add to harmonic levels inside the facility.
Data center managers also need to consider the advent of blade servers and the growing densities caused by increased demand for computing resources. Blade servers and more density require more power in the same rack space. “If blades require four to five times the power in the same cabinet, then we need to deliver that amount of power,” says David B. Mulholland, vice president of marketing and service at PDI (Power Distribution, Inc.; www.pdicorp.com). “People want to take up as little real estate as possible, so we try to get the most into the smallest space possible.”
Maximizing data center efficiency is another trend that affects power quality. “We are doing an awful lot of retrofit work,” says Mulholland. “If people can focus on the efficiency of their power food chain, they can squeeze a lot more out of it vs. investing in new data centers. In a down market, that’s what people do.” This trend can benefit power quality and prevent unbalanced loads if data center managers evaluate power usage and discover where unused potential occurs.
In today’s climate, some ways data center managers can help to ensure power quality include upgrading to online UPSes with hot-swapping capabilities, using active power-monitoring tools, and simplifying data center operations and configurations.
Select UPSes For Power Quality
Regardless of the size or type of UPS, today’s dynamic, nonlinear loads make it important to consider using an online, double-conversion UPS. “An online UPS ensures connected equipment is receiving high-quality power by continuously converting incoming AC power to DC, then resynthesizing it back to perfect AC output free of voltage fluctuations, waveform distortions, and other potential power problems common in a data center environment,” says Rich Feldhaus, Tripp Lite (www.tripplite.com) product specialist. “An online UPS can even pass generator-derived AC power during extended power failures to correct the potentially noisy output created by some generator systems.”
Your UPS power protection also benefits from supporting hot-swappable replacement or upgrades of major system components. “At times, UPS power modules may fail a regular self-test operation, require routine battery replacement, or require a power module upgrade. Using UPS products that support hot-swappable batteries and modules gives you far less reason to need to bring your network down for maintenance when the time comes,” says Feldhaus.
Install Active Monitoring Tools
Finding ways to increase efficiency requires monitoring what is being used, which also benefits power-quality management. “Data centers have UPSes, PDUs, servers, etc., but they don’t know how much power they have left, so they start checking it out the old-fashioned way with a meter and clipboard,” says Mulholland.
But the old-fashioned method does not provide an accurate sampling of power use. For a better picture of power use, you can install branch circuit monitoring software and devices for your distribution equipment. “Branch circuit monitors let you see down to the breaker level how much power is being pulled,” says Mulholland.
For even more data, you can monitor the PDUs that power your racks. Feldhaus notes that some PDUs offer a built-in amperage meter that can report the amount of power consumption in real time, with some models supporting additional network reporting as user-configurable amperage thresholds are met. “This readout offers continuous information on the amount of power connected equipment is pulling so that a network manager knows when to add additional electrical capacity, UPS systems, and PDUs to accommodate the increase,” continues Feldhaus.
Simplify It
Power-quality problems are often caused by human error. Simplifying your data center
to reduce system complexity makes it easier to manage and reduces power-quality problems. You can do this by working toward standard or modular configurations, reducing the number of devices power must pass through, and automating common tasks such as discovery and inventory management, patch management, and server provisioning.
According to Gartner, one of the key takeaways from its data center conference in 2008 was that data centers need to become more flexible through a modular approach, one that separates data centers into self-contained pods or zones, each with its own power feeds and cooling. “Tomorrow’s data center is moving from being static to becoming a living organism, where modeling and measuring tools will become one of the major elements of its management,” says Rakesh Kumar, vice president of research at Gartner. “It will be dynamic and address a variety of technical, financial, and environmental demands and modular to respond quickly to demands for floor space.”
Analyzing the number of branch circuits and simplifying the amount and types of wiring, cabling, and switching are ways to reduce complexity. And new equipment is being engineered to support more power-protection needs.
With careful planning, consolidation, virtualization, and automation can simplify data center operations. Implementing these technologies also requires an investment in deployment time, staff training, and equipment. However, the cost savings and total cost of ownership over time can make such changes worthwhile.
Every Data Center Is Unique
Ensuring that critical networking equipment receives high-quality power within a data center environment is not a one-size-fits-all proposition. As data centers, technologies, and power usage evolve, facility managers, IT staff, and management must make decisions about network reliability and availability, without overlooking the importance of power quality.
Strictly speaking, there is no single best way to ensure power quality for all locations and budgets, notes Feldhaus. “Regardless of the scale, there is no substitute for employing the expertise of a network electrical specialist who can design a power system to match the desired level of reliability your facility must attain.” 
by Carmen Carmack
Top Tips
• Redundancy is often the focus of availability planning within data centers. But don’t overlook the importance of monitoring branch circuits. If a server has redundant A and B power supplies and one fails during a peak demand time, the power level needed to continue operations with the remaining power supply may exceed the branch circuit load.
• Plan for growth and dense rack systems. Dynamic loads, blade servers, and the quest for power efficiency can significantly affect power in your data center. “Each item powered in your rack pulls a specific amount of power on a typical and peak level,” says Rich Feldhaus, Tripp Lite (www.tripplite.com) product specialist. “It’s critical that you size your electrical throughput to each device with the peak power demands your configuration may encounter.”
• Investing in high-quality commercial-grade circuit breakers helps reduce downtime. Many data centers mistakenly install the same quality of circuit breakers found in residential electrical wiring. For branch circuit breakers, look for UL489-compliant devices. Also, if you need a circuit breaker only as a disconnect, get one with a nonautomatic trip.
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