VMware has insisted the "high quality" of its virtualisation products is what enables it to keep ahead of competitors, like Microsoft, who offer free rival technology.

"People will often try and start with Microsoft first, because it's free. When they've tried it, and they try VMware, their experience [with us] is more robust.

"Microsoft plays up the point that it is about cost. VMware is built on reputation," said Rick Jackson, chief marketing officer at VMware, at the VMworld conference in Copenhagen.

Recently, Microsoft also said in a white paper that its private cloud is much cheaper than that of VMware, following the introduction of the latter's new vRAM-based pricing. It claimed that a private cloud built with Microsoft can cost up to £43,000 less than one built under VMware's licensing schemes.

It admitted, however, that its calculations were based on licensing assumptions that were not available in the real world.

VMware changed the pricing model for its vSphere product when it launched a new version earlier this year. It introduced a new metric, virtual RAM (vRAM), with pricing tied to the amount of vRAM configured to a virtual machine and tiered according to a "high-watermark" vRAM limit.

Although the company said that only five percent of customers would be affected by the change, immediate feedback was negative as costs rose for some customers, and VMware was forced to increase vRAM limits.

However, Jackson said that the new licensing model only had a negative effect on a small proportion of its customers.

"On our best estimates, we're talking about less than two percent have had a negative impact. A significantly higher percentage will have benefited from the pricing changes," he insisted.