Virtualisation brings the promise of cost reductions though IT consolidation and the efficient use of resources. In fact, the technology is so transformational, according to analyst firm Gartner, that it will be the highest impact, trend-changing infrastructure and operations technology right up until 2012.
Storage and networking virtualisation are now mature technologies, and server and PC virtualisation are becoming more pervasive, noted Philip Dawson, vice-president and distinguished analyst at Gartner.
However, experts have warned that before embarking on a virtualisation pilot, it is worth being aware that the new technology may involve unexpected costs, as well as licensing and management considerations. Organisations may also need to upgrade network and server resources to get the best out of a virtualised infrastructure.
Virtualisation and automation vendor Parallels warned prospective virtualisation users that they needed to consider the costs of virtualisation very carefully, as well as the timeframe in which they expect a return on investment.
"The current economic environment is putting additional pressure on realising savings on the total cost of ownership of virtualisation, and the speed at which these benefits can be reaped," said Serguei Beloussov, chief executive at Parallels.
He added that the right mix of servers, power, cooling, system administration and other IT factors, is crucial to the efficiency of the virtualised infrastructure. "Check the real-life density for your virtualisation solution, as it translates directly into cost savings," said Beloussov.
Virtualisation can also bring licensing issues, and vendors, analysts and users alike have complained about the complexity of different software licensing models - even from the same vendor.
For example, when it comes to licensing Microsoft Windows on a virtualised infrastructure, there are many considerations, said Mark Wilson, senior customer solution architect at Fujitsu Service.
He noted that Windows Server 2008 standard edition and later includes the right to run one virtualised operating system environment (OSE). Windows Server 2003 R2 enterprise edition and later includes the right to run four virtualised OSEs, as does Windows Vista enterprise edition.
However, Windows Server 2003 R2 datacenter edition and later, and Windows Server 2008 for Itanium-based systems include the right to run an unlimited number of virtualised OSEs, provided that all physical processors are licensed and the user has the right number of client access licenses.
Applications running in the virtual environment are generally licensed as they would be in a physical environment, and per-processor licensing, for virtualised applications, relates to virtual CPUs. However, not all vendors license their virtual applications the same way.
As well as the cost and licensing issues, virtualisation can bring management problems.
Tom Brand, consultant at Morse, explained, "Too many organisations still haven't grasped that the management strategies and tools involved are far more complex than with traditional physical environments."
He said that 62% of UK businesses are unaware of how many virtual machines are on their networks. Brand added that organisations need to implement strategies from the top down, providing clear ownership of the virtual environment and controls over creating, managing and retiring virtual machines.
Any pilot scheme must be used to ensure these strategies are correctly implemented, and to understand the dynamic relationships between virtual and physical machines, said Brand.
Colin Fisher, regional director at VMWare specialist Veeam, agreed that "the main barrier to successful virtualisation" is management.
"The tools, skills and strategies that have worked so well in physical environments are unfortunately quite unsuitable for virtualised ones," he said.
Right tools for the job
Fisher said that, before embarking on a virtualisation project, organisations need to examine how they will manage the new environment, and ensure that they have the right tools for the job. "Without these, businesses will quickly find themselves watching over an ungovernable sprawl."
Despite the obstacles, many organisations are reaping the rewards of a virtualised IT infrastructure.
One of the top attractions of virtualisation is the 'green' angle.
"A business opting for virtualisation will experience significant cost and CO2 savings," said Chris Shaw, managing consultant at NCC Group.
"If the number of servers is cut from 30 to three, the associated electricity bill could drop from almost £11,000 to just over £1,000. CO2 emissions could drop from 64.71 to 6.47 metric tons, the equivalent of taking nearly 10 cars off the road every year," said Shaw.