Virtualisation is eating away at the x86 server market reducing revenue by four per cent in 2006, according to Gartner.

The analyst firm predicts more than four million virtual machines will be installed on x86 servers by 2009.

On the client side, the number of virtualised PCs is expected to grow from less than five million in 2007 to 660 million by 2011.

In a special report released today in the lead up to Gartner's infrastructure, operations and data centre summit in Sydney next month, the analyst firm has identified virtualisation as the highest-impact trend affecting IT operations through to 2012.

While virtualisation is hardly a new concept, Gartner managing vice president, Phil Sargeant, said it is creating a new wave of competition among technology vendors that will result in considerable market disruption and consolidation over the next few years.

Sargeant said storage has already been virtualised - albeit primarily within the scope of individual vendor architectures - and networking is also virtualised.

"However, with both server and PC virtualisation becoming more pervasive, traditional IT infrastructure orthodoxy is being challenged and is changing the way business works with IT," he said. According to Gartner, the leading edge of this change is server virtualisation, which promises to unlock much of the underutilised capacity of existing server architectures.

As hypervisor prices drop sharply and management costs decrease because of increased competition, virtualisation will have a significantly larger impact. Moreover, the use of PC virtualisation is also set to increase rapidly.

On the PC, the decoupling technology that breaks the close ties and dependencies between hardware and software occurs at two levels: between hardware and the operating system (machine virtualisation) and between the operating system and applications (application virtualisation). Although application virtualisation is gaining considerable interest, Gartner maintains that it is machine virtualisation that will have a longer-term impact, making personal computing more manageable, flexible and secure by allowing multiple individual footprints to be defined on the same device. "Essentially, virtualisation creates a fork in the road for operating systems," Sargeant said.

"Traditionally the operating system has been the centre of gravity for client and server computing, but new technologies, new modes of computing, and infrastructure virtualisation and automation are changing the architecture and role of the operating system.

"The days of the monolithic, general-purpose operating system will soon be over." Sargeant said infrastructure vendors that have always vied for the largest share of budgets on a best-of breed basis must alter their approach.

He said in the future, the virtualisation and automation of infrastructure will be managed by policies at a business-service level, requiring all parts of the infrastructure to work in harmony.