Unscheduled outages were occurring almost monthly at Pacific Northwest National Laboratory, bringing down the data centre for hours at a time. Groups were buying an increasing number of rack-mounted servers - which had recently become cheaper at the time - to boost the computing resources, says Ralph Wescott, data centre services manager for the government laboratory, which is managed by the US Department of Energy. In July, 2005, the server room had reached its capacity limit.

"Groups would go buy a server and throw it over the wall to me, saying, 'Hey, install this,'" Wescott says. "But I didn't have any space, power or cooling (capacity) left. If I installed (one more), the whole room would go dark."

Wescott and PNNL embarked on a broad project to revamp their data centre without breaking the budget. Every quarter for three years, the data centre group spent a weekend shutting down the server room and replacing a row of old servers and tangled network cables under the floor with more efficient, yet more powerful servers connected by fewer cables running in the ceiling. The new configuration allowed for more efficient cooling under the floor.

The result? PNNL moved from 500 applications on 500 servers to 800 applications running on 150 servers.

During a tight economy, tackling such information-technology projects require a tight grip on the purse strings, says Joseph Pucciarelli, the program director of technology, financial and executive strategies for analyst firm IDC, a sister company to Techworld.com.

"The situation is a very common one," he says. "Companies are making just-in-time investments. They have a problem, and they are looking at the problem in a constrained way."

Here are some lessons PNNL learned in bringing their data centre back from the brink.

1. Plan, don't react

The first problem Wescott needed to solve was the data centre group's habit of reacting to each small problem as it arose, rather than seeing the systematic issues and creating a plan to create a sustainable service. In addition to the 500 servers, the data centre had some 33,000 cables connecting those servers to power, networking and security systems.

"We decided what the data centre should look like and what its capacity should be," he says.

The group concluded that the current trajectory would result in 3,000 applications, each running on its own server, in 10 years. Now, the data centre has 81 percent of applications virtualised - and average of 17 per server - and Wescott plans to reach the 90 percent mark.

Companies should focus on three areas to increase capacity, says IDC's Pucciarelli. Reducing the number of physical servers and running applications on virtual systems helps reduce power requirements, as does more efficient cooling systems and improvements in electrical distribution.

"That's typically the one-two-three that you go to when updating the data centre," he says.

Pucciarelli has encountered many companies that have replaced up to 50 servers with just two or three larger capacity systems and used virtualisation to run their applications.