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Processor Magazine
– September 2008
The latest hardware has certainly made it much easier to pack a lot more horsepower in a smaller package. Blades, of course, have shrunk the form factor of the average server, and quad-core chips make it possible to quadruple the amount of juice in the same footprint.
“Blades are the fastest-growing segment in the server market,” says John Enck, an analyst at Gartner.
Now factor in virtualization. By setting up 10 virtual machines in a single blade, you are going to be taking up every possible unit of processing power—the only problem is that you are going to be generating a whole lot more heat.
“The adoption of high-density servers has been somewhat of a forced migration,” says Kenneth Wolverton, vice president of data center operations at CyrusOne (www .cyrusone.com). “Like the evolution from cassette tapes to CDs, manufacturers are simply not offering or supporting legacy technology.”
Analyst firm IDC has noted that approximately 75% of SMEs are in the process of implementing high-density computing platforms. By 2012, that number will approach 100%. Unfortunately, this effectively renders the existing power and cooling infrastructure obsolete.
According to CyrusOne, traditional data centers operate at approximately 100 watts per square foot. A high-density infrastructure, on the other hand, requires an average of 250 watts per foot. For example, high-density blade servers operate at 50 amps, a major increase over previous server generations that typically ran at 20 amps. As a general rule of thumb, it takes $1 (of utility power) to cool every dollar in direct consumption in a high-density data center.
“To temporarily alleviate cooling challenges, users are inefficiently spreading out their high-density systems across rows of their data centers,” says Wolverton. “This minimizes the usages of white floor space and requires the installation of additional computer room AC (CRAC) units.” He offers some recommendations to avoid overheating in highly dense spaces:
Architecture. The subfloor ventilation and perforated tiles should be designed and laid out using engineering-driven schematics that maximize output and availability for any emergency overheating situation. Ventilation in a high-density environment requires a minimum 3-foot raised floor to accommodate necessary subfloor equipment. Racks should be set up in a hot aisle/cold aisle configuration with dual airflow designed to effectively disperse cold air into the cold rows and to pull hot air off the hot aisles, minimizing the mix of cold and hot air.
Tools. High-density data centers should take advantage of a CFD (computational fluid dynamics) simulation to engage the entire layout of the data center and run through all the “what if” scenarios to identify hot spots and potential problem areas. CFD simulations can also be used to identify the strategic placement of CRAC units to ensure that optimal airflow can be diverted and/or increased to any potential hot zones.“SMEs should make capital investments in existing infrastructure to upgrade their data center to accommodate high-density, i.e. additional CRAC units, rearchitecture of aisles, and using tools like CFD,” says Wolverton. “Alternatively, they can select a high-density colocation that guarantees availability, scalability, and increased watts per square foot.”
Winning The Battle
Phil Francisco, vice president of product management and marketing at Netezza (www.netezza.com), says that in the coming years, SMEs will battle to bring power consumption under control.
“Industry analysts predict that soon, 50% of data centers won’t be able to cool off,” says Francisco. “According to IDC, by 2009, technology operations in the U.S. will spend twice as much for power and cooling as they did to buy the server hardware in their data centers.”
He feels the solution lies in specially architected racks and appliances tailored to specific purposes, such as data warehousing, storage, and supercomputing. These customized solutions are being designed with much greater energy efficiency, lower power consumption, and a smaller footprint.
Alternatively, some SMEs may find that it is simply more efficient to implement blades and virtualization in a colocation facility. Some of these organizations have the resources to implement state-of-the-art cooling and power architectures that most SMEs can only dream of.
Shoe retailer Zappos.com, for example, uses colocation to host its IT services. As a result, it can pack blades as densely as it wants into a small space. It began with four racks and built the IT side of a $700 million success story around that hosted hardware. It has expanded now to a large cage of hardware at the colocation facility.
But it makes a difference which colocation facility you choose. One company, for example, wanted to deploy 38 racks packed with blades and pizza box servers and asked various colocation facilities for an estimate of costs. One provider has the cooling and power infrastructure to support all those racks in 720 square feet. Others with less efficient cooling setups estimated up to 16,000 square feet of rented space with each rack spread around with a minimum of 20 cubic feet of air circulation. You can guess which vendor quote would be the highest.
So check just how much power your potential colocation facility can accommodate. In the paragraph above, the quotes ranged from 17kW per rack to 1kW per rack.
by Drew Robb
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