Almost anyone who has worked on mainframe or enterprise Unix systems will be acquainted with the concept of Virtual Machines. However, managers of Windows based systems have, on the whole, less familiarity with the idea and more importantly still, with the significant benefits that the utilisation of such an approach can deliver.

In essence the main idea behind the virtual machine concept is to make it possible for a single server hardware platform to play host to multiple virtual machines. Each virtual machine operates as if it was loaded onto its own hardware platform to which it has sole access and it is often possible to load many virtual systems onto a single physical server. In some scenarios it is even possible to load virtual machines that emulate different operating system environments onto a single physical platform.

In the Windows world one company, Connectix, has taken this concept to a very advanced state. For some time now the company has offered two products in the desktop marketplace. Virtual PC for Windows allowed users to use a range of applications that might only operate on specified environments, such as Windows XP, 2000, NT, 98, 95 and even Windows 3.1 along with support for DOS and OS/2, all on a single PC. In addition the software also enables users to run Linux, Solaris and Netware environments on the same PC. A similar product, Virtual PC for OS/2, allows OS/2 machines to host a similar range of operating systems and associated applications.

Recently, Connectix has extended these ideas with the release of its Virtual Server product to extend its virtual machine capabilities into the server space. The isolation of operating environments within hardware environments offers many advantages to users, especially in terms of manageability and reducing the total cost of ownership associated with running systems.

The Virtual Server software effectively allows an entire operating environment and application(s) to be packaged into a container that is stored as a single file. This container can then be loaded onto a server hardware platform where it functions as if it owns the entire system. The virtual machine has no knowledge at all of whether any other virtual machines are running on the hardware.

In this way it is possible to operate multiple environments on common hardware, even to the degree of them hosting different operating systems or making it possible to run applications on the same device that would not normally be supported. For example, using this technology it is possible to run both Microsoft Exchange and IIS on the same hardware platform, a combination not recommended by Microsoft.

Having entire environments stored as containers allows them to be rapidly distributed to server hardware platforms to cater for surges in service demand that require the allocation of additional resources. In the same way, it is possible to evaluate upgrades or new applications in total isolation from the live environment and make them available rapidly when testing has been completed. The virtual machine approach to system management helps manage the risk associated with any changes that occur or project work that needs to be accommodated.

It is clear that the use of containerised virtual machines that make it possible to divorce applications and operating systems from the underlying hardware deployed in the Windows / Intel environment has much to recommend it as a management tool. Cost Avoidance, Manageability, Risk Reduction and Flexibility are all enhanced by using this type of architecture. For players such as Connectix and other suppliers of virtual machine technology, including VMWare, the Intel server world may be about to witness an explosion of interest.