In an era of rising power use and costs, efficiency is job one. The issue: What's the best way to cool your data center, plug holes and minimize your footprint.
Data center managers are on the hot seat lately. They not only have to cram in more servers per square inch than they ever wanted or thought theyd need, they also have to figure out how to do it without sending the electricity bill through the roof.
And theyre not entirely sure how to do it.
Traditionally, theyve had to worry only about getting as much power in as possible, not about making sure they used it efficiently.
"When it comes to data centers, cost isnt irrelevant, but its not about cost. Its about uptime," said Rick Oliver, data center operations senior engineer at the University of Phoenix, a for-profit online university based in Phoenix.
So, as companies have built new facilities, its been more important to overbuild than underbudget. That has meant adding in as many air conditioning and other environmental controls as they practically could and talking the local utility company into running in as many redundant power lines as they ever expected to need.
"You go in thinking about the future, about the systems were going to have, and about heating and cooling them, in three years or five years," said Seth Mitchell, infrastructure team manager for Slumberland, a furniture retailer based in Little Canada, Minn.
"You have to extrapolate where youre going to be because building a [data center] room is a fairly permanent thing. Its not easy to make changes to a permanent design."
Not that Mitchell has much of a choice. Escalating energy costs, which seem to rise with every new conflict in the Mideast or with every Alaskan oil pipeline problem, are causing customers and technology vendors to rethink the data center.
On Aug. 16, engineers at the Lawrence Berkeley National Laboratory and about 20 technology vendors concluded a demonstration of DC power in a data center.
Hewlett-Packard is looking to nature to redesign the data center of the future, and suppliers ranging from Advanced Micro Devices to Intel to Sun Microsystems are trying to cut power costs.
Click here to read more about Sun offering power rebates for its servers.
"The people who spec and build the data centers are not the ones who pay the electric bill," said Neil Rasmussen, chief technology officer and co-founder of American Power Conversion, in West Kingston, R.I. "Many of them didnt know what it was or even who paid it."
As a result, data center managers are doubling as HVAC (heating, ventilating and air conditioning) experts as well as certified IT administrators.
In their efforts to "green" the data center, they are learning to unlearn a lot of data center architecture design that has been handed down over the years.
Any data center, but especially one crammed with servers stacked in compact chassis, is "a radical consumption of power, and the exhaust of power is heat; there is no way you can consume one without the other," Oliver said.
But as the typical server unit has shrunk from a stand-alone pedestal the size of a filing cabinet to 2U (3.5-inch) stackables, 1U (1.75-inch) pizza boxes and even blades, both power and heat cause problems.
"The whole industry has gotten hotter and more power-hungry. Within the last five years, servers went from using around 30 watts per processor to now more like 135 watts per processor," Oliver said. "You used to be able to put in up to six servers per rack; now its up to 42."
Every kilowatt burned by those servers requires another 1 to 1.5 kW to cool and support them, according to Jon Koomey, a staff scientist at Berkeley National Laboratory, in Berkeley, Calif., and a consulting professor at Stanford University. Koomey has studied the cost and efficiency of data center designs.
Efficient systems depend on a circuitous power flow. "You bring the power in AC from the wall, convert it to DC through the battery backup, back to AC to the server, then to DC for the chip," Koomey said. "Theres an awful lot of power loss in that."
But even under ideal circumstances, most data centers are forced to buy more chassis than they really need and leave them partially empty to allow the heat to dissipate, Koomey said.
"If you put the most densely packed devices on the market now, whether they were blades or whatever, and you packed them [in full chassis] into data centers fully, you couldnt cool it," Koomey said.