The market for PC virtualisation software comprises products that enable users to run one or more virtual machines (VMs) on a physical PC. This type of virtualisation occurs between the guest OS running in the VM and the host hardware.
This approach is not new, and products targeting some technical uses have been available for years. Since 2006, the range of available products has expanded and new use models have emerged, doubling the number of virtualised PCs during 2007. Gartner estimates that the number of virtualised PCs increased from 4.6 million to 10.6 million during 2007.
Although licensing changes from Microsoft will drive new demand, they will also signal a point of inflection in growth for the PC virtualisation software marketplace. In the longer term, the ability to run VMs will become a default part of the basic PC capabilities, embedded in motherboard and OS functions. Use of virtualisation will expand significantly, but the market for standalone PC virtualisation software will contract
Each VM created with PC virtualisation software is a logical partition that has complete virtual PC hardware resources into which a PC OS can be installed. The layer of virtualisation software intercepts requests from VMs for virtual hardware resources and maps these to the physical hardware resources of the PC.
This process can be multiplexed (and prioritised), so multiple VMs can be supported in parallel. In most cases, PC virtualisation software is used to run multiple operating systems simultaneously on the same physical PC.
The process of virtualisation decouples the OS in each VM from the confi guration of the physical hardware, so VMs are portable between hardware confi gurations.
There are two types of PC virtualisation software:
- Hosted, where the virtualisation layer runs on top of a host OS. The virtualisation layer is installed as an application, so almost any PC can be virtualised. The downside of this approach is that the host operating system duplicates some of the processing of guest operating systems, so the process of virtualisation adds significant performance overhead.
- Hypervisors, which run directly on hardware. Hypervisors are thin layers of virtualisation software that have much less impact on the performance of software running in the VM, but running the Microsoft Windows OS on a hypervisor requires hardware virtualisation support. This is available on some, but not all, newer PCs.