Data centre managers have embraced server virtualisation in the past year, across a variety of businesses for nearly every kind of application, as a way to reduce oversight and hardware costs, reckon IT managers and analysts at Infrastructure Management World.

Several IT managers interviewed at the recent conference in the US said that there is no downside to server virtualisation, adding that the trend is firmly implanted in their IT shops. More than half of the 400 attendees at IMW indicated in a survey that they are deploying server virtualisation in their shops or plan to do so.

Users interviewed by Computerworld said they are using commercial virtualisation software from VMware, although some are testing open source software obtained through XenSource. Open source options have the potential to cut virtualisation costs, but some IT managers were sceptical of them.

"We see virtualisation as a trend that's not going away," said Lee Congdon, vice president of corporate technology at Capital One Financial. Capital One is midway into a three-year plan to add virtualisation software to Windows-based servers, a move that will reduce the number of servers at the company from 1,600 to 1,100, Congdon said. He noted that the company has already seen "substantial" cost savings as a result of the transition.

IT managers said they don't need as many server administrators -- or as many server boxes -- to run virtual servers.

Congdon said Capital One has used the technology to grow faster as a more full- service bank, moving beyond its image as a credit card company. Financial applications used by newer business units can be added to a collection of servers instead of giving every new application its own server, he added.

Using server virtualisation, the time it takes to provision a new server has dropped from eight weeks to just two weeks, Congdon said. That reduction has made it possible to support faster application development cycles -- something the bank needs as it grows.

Server virtualisation is most often used for routine tasks that aren't vital to companies, according to analysts. But Congdon said that even mission-critical applications can be run on a virtual server.

Capital One is evaluating the use of open source virtualisation, said Congdon, although he would not name any particular software.

Detroit Medical Centre, which has nine hospitals in that city, has been using virtualisation software for three years and expects to expand beyond the 20 servers now partitioned into four virtual servers apiece, said John Karras, the centre's director of technical services. So far, the virtualisation process has allowed a 40 percent increase in servers without requiring more server administrators, he said.

Karras is sceptical of using open source software in a medical environment. "The problem is that there's nobody to call" if a problem arises, he said. "And if there is somebody to call, it means it's not really open source and you'll be paying for support."

Server virtualisation is also being used in smaller companies. Riester, an advertising firm with 100 employees, has been using a single-server box with three virtual servers running on VMware, said IT director Dan Peterson. He said the cost of VMware has pushed him to consider XenSource, which he is testing now. VMware charges for management software, which Riester is trying to avoid. Peterson also said he doesn't have any reservations about trying open source in his shop.

IDC estimates that nearly 500,000 server boxes equipped with virtualisation software will ship this year, up from just above zero three years ago. By 2009, the number of units shipped is expected to reach 1.2 billion, the research firm said. "I'm shocked by the level of adoption of virtualisation," IDC analyst Michelle Bailey told a conference audience.

She said VMware dominates the commercial server virtualisation market, competing with Microsoft, SWsoft and Cassatt.