Achieving Balance

Air conditioning systems perform most efficiently when the temperature differentials are higher, so Glumac implemented changes that made the cold aisles colder and the hot aisles a few degrees warmer. "We weren't optimizing the heat-to-cooling ratio that the AC units needed. You have to get that balance," Patterson says.

To address that thermal layer problem, Glumac engineers adjusted the CRAC system by raising the height of the air-return intakes by one and a half to two feet. That pushed the thermocline layer above the tops of the racks, providing a better thermal environment for equipment located there.

Once the airflow balance was achieved in the aisles, engineers turned their attention to what was inside the racks. "There's an optimal temperature point where you want your chips running," says Patterson. With that in mind, Scottrade reorganized the racks, moving power-hungry servers lower to balance the heat distribution within the racks.

It also helps that Scottrade's new data center is using energy-efficient servers. The 1U and 2U blade server models it has chosen use low-voltage processors, variable-speed fans that accelerate and decelerate depending on processing power consumption, and high-efficiency power supplies. (Those units came with virtualization software embedded on ROM, making setup easier.) "It draws less energy, and it keeps the internal temperatures in the boxes cooler," Patterson says.