Sun has upgraded three of its data centers in the U.S., U.K. and India to make dramatic electricity savings and cut its carbon footprint. It joins IBM and HP in offering its own data center experiences as a green example to its customers.

Sun has consolidated data center facilities in Santa Clara, as well as in Surrey, U.K. and Bangalore, India. The new data centers occupy 133,000 square feet of space, slightly less than half the original 267,000 square feet.

There were two main aspects to the new data center designs: server consolidation; and cooling efficiency advances. In the Santa Clara data center Sun has replaced 2,177 older servers with 1,240 newer multi-core SunFire T1000/T2000 and x64 servers, all running Solaris, to both reduce power needs by nearly 80 percent yet increasing computing power by 456 percent.

It is using Solaris' virtualization features to, in effect, replace physical servers with virtual servers.

The cooling system employs a variant on the hot aisle / cold aisle design, with closed pods containing racked computing equipment These need less cooling power than a traditional design, which tries to keep an entire data center at a homogenous temperature through standard air-conditioning. Only the hot areas of the pods are cooled by heat exchangers which take heat outside the data center.

Inside the pods there are temperature sensors for individual servers and the control system can focus cooling dynamically on hot spots.

Some storage consolidation took place as well. Older disk arrays were replaced with StorageTek 3000 and 6000 arrays using 144GB Fibre Channel drives. These offered higher performance and capacity increased by 244% although 70% fewer arrays were used.

The company estimates that these server, storage and cooling initiatives will reduce its carbon emissions by about 4,000 tons a year, shaving 1% off its annual carbon footprint. The Santa Clara data center will pay for itself in three years.

The cost of the Santa Clara data center project was helped by a near $1 million rebate from the local power company.

Several European data centers were consolidated onto a single U.K. site at Blackwater, a single pod in fact. One hundred older servers were replaced by 80 newer ones connected to a StorageTek 9985 storage area network (SAN) array.