Virtual transitions

Implementing desktop virtualisation at the British Museum Company has allowed IT staff more time to tackle other issues such as improving productivity

Desktop virtualisation technology has caught the imagination of suppliers recently, with IT giants such as Microsoft, Sun Microsystems and Symantec all snapping up small companies specialising in applications that run virtual copies of multiple desktop PCs on one physical computer.

But despite the apparent enthusiasm on the supply side, few companies are yet using any form of desktop virtualisation within their IT infrastructure, and it could be a few years before the technology becomes mainstream, if at all, say experts.

To understand the benefits, potential customers must first be certain about what desktop virtualisation is – ­ which is tricky, considering there are two definitions of the technology.

The first involves a server-hosted approach, employed by software such as VMware’s virtual desktop infrastructure (VDI) and Citrix’s XenDesktop, where a virtual image of a desktop PC, including the operating system, standard hardware device drivers and dependent applications, is stored on a central server and accessed through the network. The image is downloaded to the client device, whether PC, thin client or another form of computer, on demand.

The second approach sees the virtual desktop image stored on the client device itself, essentially allowing different, multiple instances of a virtual PC using different operating systems and applications to run on one desktop PC.

This client-hosted approach allows the user to switch between virtual desktops in the same way that they switch between different applications or windows now. It is favoured by Parallels and Microsoft ­ – which recently purchased Kidaro ­ – as well as some small startup companies, says Matthew McCormack, a consultant at researcher IDC’s European Systems Group.

“Desktop virtualisation is in its early days, and is still building up in terms of practical use cases and solid implementations, but there are some niche applications in software development and testing for which it is well suited,” he says. “Outside of that, some of the more sophisticated IT departments in global 100 companies have rolled out server-hosted virtualisation, but it is not common at all.”

Roy Illsley, senior research analyst at Butler Group, agrees, pointing out that using a single PC to run multiple operating systems simultaneously can allow companies to consolidate their IT footprint by a significant margin, as well as running legacy applications on operating systems which are no longer fully supported by either the IT department or the software developer.

“Desktop virtualisation is useful for certain scenarios, such as development environments which would otherwise have to use three or four different PCs running three or four different operating systems to test an application,” he says.

“Doing it all on different virtual machines (VMs) running on the same PC delivers certain consolidation advantages in those environments.”

Consolidation is rarely the reason for implementing server-hosted desktop virtualisation, however, where tighter control of the IT infrastructure can deliver desktop management and security benefits, says McCormack.

“The management benefits are clear ­ – since one copy of the VM is hosted on the server, it is easier to patch one image and roll it out rather than accessing and updating multiple physical PCs individually. It is also more secure, since the applications are running in a virtual silo which is isolated from the rest of the PC, meaning data leakage is less likely,” he says.

“Downloading full virtual images of a PC from a server is great because it provides companies with centralised management, but it must be remembered that IT managers still have to manage images.”

Desktop virtualisation is also credited with enabling enhanced security.

The abundant flow of viruses, worms and other forms of malware into user desktops is responsible for a lot of expensive downtime and support costs.

Desktop virtualisation provides the potential to minimise risk by running firewalls and other defence mechanisms in a separate virtual desktop, isolated from the rest of the PC, so that one infected desktop does not spread the virus to other virtual images. Sensitive applications running in separate virtual machines are also less open to attack from hackers.

And where security access is especially important, such as in government or financial institutions, IT departments might even want to tie different security or data access privileges to different virtual machines.