Dealing with Hot Spots in Data Centers

By Maryellen Lo Bosco  
OTHER PARTS OF THIS ARTICLEPt. 1: CFD Modeling Can Help Maximize Data Center CapacityPt. 2: CFD’s 3-D Detail Can Help Avoid Stranded CapacityPt. 3: CFD Poses Issues of In-House Training, Software PurchasesPt. 4: This Page

Hot spots in data centers cause equipment failures, add costs to cooling, and diminish energy efficiency, explains Bob Cassiliano, chairman and CEO of 7X24 Exchange International. But there are a variety of ways that hot spots can be addressed.

One is to turn off idle servers. "You would be surprised by how many unused servers are burning electricity and not performing any data processing," says Cassiliano, who is also president and CEO of Business Information Services, Inc. (BIZ). It is possible to turn on power management features that draw power based on server load.

Typical server use is about 10 to 15 percent of capacity, Cassiliano says. Virtualization allows for a greater use of server capacity and provides consolidation opportunities to reduce the number of servers in use. "Implement storage management, including such features as de-duplication, data compression, and automated storage tiering, which can reduce the number of storage devices," Cassiliano advises.

Air flow can be another culprit when it comes to hot spots. "One of the most common problems causing hot spots is bypass air flow, a mixing of hot and cold air that causes hot spots to develop, which increases server inlet temperature," Cassiliano says. "This is a particular problem at the top third of the rack." Some simple solutions to this problem are using blanking panels and sealing cable cut-outs or relocating misplaced perforated tiles.

A more sophisticated way to resolve the problem, says Cassiliano, is to use hot or cold aisle containment.

Many times when hot spots are identified, data center operators add more cooling. But by doing this, the cool air may be forced to mix with the hot air, which actually defeats the purpose of adding cooling capacity, and the end result is added expense with no actual benefit, Cassiliano explains. Some research actually shows that forcing in additional cool air causes mixing with hot air at the top of the rack and moves mixed air into the cold aisle, creating a hot spot. In many cases, shutting off CRAC units actually minimizes hot spots.

"Solving persistent hot spot problems requires utilization of special tools, such as CFD modeling, DCIM, and wireless sensors that capture data and allow you to analyze air mixing, under floor air pressure, and efficiency of the cooling system," Cassiliano says. More advanced solutions that companies will be looking toward include containment systems, liquid cooling, and various types of heat exchangers, as well as the creation of data center zones based on power loads. "Proper cooling of data centers has been and will continue to be an industry challenge," Cassiliano says.

— Maryellen Lo Bosco

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  posted on 1/24/2015   Article Use Policy

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