Thanks to a massive datacenter consolidation, hardware refresh, and creative, energy-efficient facility design, Sun has reduced power capacity demand by 75 per cent at its California datacenter alone, saving US$1.1 million per year in energy costs, while increasing its datacenter processing power more than four times. Overall, Sun estimates that its consolidation efforts will save 4,100 tons of CO2 per year and cut 1 per cent from its total carbon footprint.

Sun's consolidation grew out of twin promises to reduce carbon dioxide emissions by 20 per cent from 2002 levels by 2012 and to achieve a 4 per cent operating margin by shedding real state, consolidating datacenter space, and saving energy costs. In order to maximize its energy savings, Sun not only consolidated all its datacenters down to three -- one each in California, the UK, and Bangalore, India -- but the company refreshed its datacenter hardware with more energy-efficient machines and reassessed its entire approach to datacenter design.

"We discarded the traditional raised-floor, whole-room approach to datacenter cooling in favor of a slab floor and a modular design based on 'pods,' stand-alone structures with their own individual airflow management, integrated cooling power, and network distribution," says Mark Monroe, Sun's director of sustainable computing.

A pod is born

Sun uses multiple APC hot aisle containers, each of which holds two opposing sets of racks back to back and is closed off with a roof and doors to prevent hot and cold air from mixing within the datacenter. Overhead piping and Liebert XD cooling units target each rack individually, directing cooling exactly where it is needed, rather than cooling the room as a whole. This increases energy efficiency dramatically and lets Sun scale cooling closely with processing power. "We've reduced our power draw in Santa Clara from 2.2 MWs to 560kW using this design," Monroe says. "We also achieve efficiency by keeping the chillers, power distribution systems, and UPSes close to full capacity at all times, rather than the 50 or 25 per cent of capacity typical of many datacenters."

In-row APC chilled-water cooling units supplement the overhead units and can sense and react to changing local temperature conditions, so if a 5kW rack is replaced with a 2kW rack, the fans scale down automatically to save power. Sun estimates that scaling back fans by 50 per cent reduces power consumption to one-eighth of what it is at 100 per cent.

Sun's modular approach also allows for a lot of flexibility and growth. "We can scale power and cooling dramatically without having to change the overall datacenter design," Monroe says.

This is obviously important as racks are likely to get more powerful over time. For power distribution, Sun uses Universal Electric's Starline Track Busways, which are based on a snap-in backplane design similar to track lighting. "Over the life of the datacenter, the Starline systems will save about 50 per cent of the copper used in power distribution," Monroe says.

Finally, more energy is saved by the use of Sun Fire T1000 and T2000 servers, which Sun claims can reduce power consumption by 30 per cent over competing machines. Sun diverted some of the capital expenses used for construction to pay for the hardware refresh.