Enterprises are holding back on virtualisation projects because users are faced with too high a price for the technology. Vendors are penalising companies for running applications on virtual machines rather than physical ones, according to a new report from the The Burton Group.

"There is an abundance of user angst and uncertainty surrounding the licensing and support of applications running on x86 virtualised environments," writes Burton analyst Chris Wolf. Some vendors simply won't support their applications when they run inside VMs, states the report, titled Virtualisation Licensing and Support Lethargy: Curing the Disease that Stalls Virtualisation Adoption.

But software providers can make life difficult and more expensive for customers even without such an all-or-nothing approach. Vendors sometimes will support applications on virtual servers only if they run on certain platforms, typically VMware ESX Server, Wolf writes.

Sometimes they tie licences to hardware components that may change as VMs relocate from one physical host to another, or penalise customers for maintaining offline copies of virtual machines for disaster-recovery purposes.

Frustrated customers "often deal with software vendor support by either 'accidentally' failing to disclose that an application is running in a virtual machine (VM) or by cloning the VM to a physical server before calling support," Wolf writes.

The Burton Group recommends that vendors develop common licence management standards, and remove all restrictions on VM mobility in product licensing. The analyst firm gives high marks to some vendors, such as SAP, which has employed virtualisation architects to help write policies "fully compatible with modern virtualisation architectures."

The 51-page report reviews vendor policies in three categories: server operating systems, management applications, and client-server applications or middleware.

Server operating system licensing policies are "generally virtualisation-friendly" with a few exceptions, while there are more problems on the application front, with independent software vendors often binding application licenses to physical server hardware.