Virtualisation is set to be the biggest driver in IT for several years, according to a report from Gartner.

The research firm called virtualisation the "highest-impact trend" for IT through 2012, predicting it will determine how IT administrators manage, buy, deploy and plan their future strategies. And it won't just be the major enterprises that jump on the virtualisation bandwagon either.

"To be honest, most of the growth for virtualisation thus far has been in the (large) enterprises," Phillip Lawson, vice-president and distinguished analyst at Gartner, said. "VMware has been fairly monolithic in its success, but we think as Microsoft enters we're going to see the mid-range and smaller enterprises really open up and adopt virtualisation."

The driving factor behind the growth, according to Gartner, will be server virtualisation, which the research firm said contributed to a four percent drop in the x86 server market in 2006. The report states that about 90 percent of the server market is composed of x86 architecture servers. Based on the traditional model of one application per server, Gartner said, roughly 80 to 90 percent of server computing capacity is unused.

Gartner analysts also predict that more than four million virtual machines will be installed on x86 servers by next year - which is almost as many virtual PCs in operation today.

And with server virtualisation allowing organisations to quickly provision virtual machines within a matter of minutes, Gartner said another strong factor in the virtualisation boom will be the significant growth of virtual PC deployment. The research group expects the number of virtualised machines to grow from fewer than five million in 2007 to about 660 million by 2011.

Some in the virtualisation space believe the success of Microsoft's Hyper-V will ultimately determine virtual machine deployment numbers over the next few years.

"Microsoft's Hyper-V could drive that number in any direction really," Andrew Hillier, co-founder and CTO at Ontario-based server virtualisation firm CiRBA, said. "We've also seen some very interesting things from vendors like Citrix, where it's quickly building the ability to virtualise both the server and the client side."

With the virtualisation industry already starting to get a little crowded, Gartner said enterprises can expect this competition to play out both in the market and in the users' IT infrastructure. As a result, the research firm advises virtualisation adopters to avoid following one specific vendor's vision and develop their own heterogeneous infrastructure.

"You need to understand your own application portfolio, what to virtualise and what not to virtualise," Lawson said. "Have a pragmatic approach to virtualising your infrastructure and don't assume one size fits all." Lawson said the factors that will help drive this along are broader scaling of virtualised environments in the hardware and better common management processes for the applications.

"If you look at the system management capabilities of virtualisation vendors, it's not the big players that are succeeding at the moment, it's all the small tools guys," he said.