Dumping The Old Air Conditioner

Although other vendors including Liebert (a subsidiary of Emerson Network Power) also make in-row cooling equipment, McPhearson first learned about the approach after seeing a demonstration of the InfraStruXure equipment in the back of a truck that APC had taken on a promotional tour. Initially, he found it difficult to convince senior management that the compact APC cooling equipment would be able to succeed where the old air conditioner had failed. "They couldn't get their heads around the idea that these two APC units, which fit in about 8 square feet, could do the same job as our 10-ton Liebert covering 25 to 30 square feet of floor space," McPhearson says.

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After visiting an APC facility in St. Louis, however, the Cimarex managers were convinced to give it a try. While continuing to run the Liebert air conditioner, McPhearson began migrating servers and network equipment into the APC racks a piece or two at a time. "Pretty soon, we wound up migrating all of our stuff from the old server room to the new server room," he says. "The only thing we have left in the old server room right now is those two Network Appliance boxes." By the end of the year, he plans to move those over as well and retire the old 10-ton air conditioner.

Although the move to in-row cooling was originally driven by a crisis with overheating equipment, it also had a financial payoff, McPhearson says: "We weren't trying to drive down electric use and cost, but those savings have in fact materialized as an unintended benefit."

McPhearson and his staff had to learn how to calibrate the equipment properly. At first, they had a tendency to adjust the "set point" at which the air conditioning would kick in too low, at about 68 degrees. That seemed reasonable to a staff used to a traditional data center cooled to 50 or 60 degrees in an effort to counteract the hot air circulating through the room. Gradually, they learned that they could adjust the set points between 72 and 75 degrees and still keep the temperature within the server racks to an acceptable level. "That's what saves you the cooled water," McPhearson says.

Another benefit of the APC rack and cooling design: Cimarex could pack more equipment into less space, without causing overheating issues. The effect was multiplied by a virtualization effort Cimarex was pursuing at the same time, using VMware technology to consolidate the workload of 38 or 39 physical servers onto two servers hosting multiple virtual machines.

Andrew Terminesi, the APC account manager who worked with Cimarex, notes that the cost savings numbers tend to look more impressive for much larger installations. Even though Cimarex is a billion-dollar company, the Tulsa data center is really a modest-size computer room equipped with just eight InfraStruXure racks. "The savings in floor space is one of the major benefits they realized from this kind of installation, since traditional data-center racks and cooling are very space inefficient," Terminesi says.

The last thing McPhearson says the arrangement provides is peace of mind. Whenever the old cooling system failed—and it happened twice in the year prior to the APC implementation—the server room would heat to 118 degrees within 15 minutes, and servers had to be shut down manually to avoid permanent damage, he says: "This is why I am so fond of the new system all being tied together; if we lose chilled water, the system powers down gracefully before we see heat issues."