Desktop virtualisation is becoming increasingly attractive to enterprises, particularly mid-sized businesses that have achieved significant data centre efficiency improvements through server virtualisation.

However, while server virtualisation mainly concerns back-end server consolidation, the move to desktop virtualisation involves re-architecting major parts of the IT system and making big investments in server hardware and network infrastructure, virtualisation management software and virtual application licences. The return on investment tends to take several years.

Nevertheless, an increasing number of organisations are investigating desktop virtualisation technology, which can bring a whole host of IT and management benefits.

Recent research from Gartner found that slightly more than 10% of mid-sized organisations have deployed desktop virtualisation in production, and around 30% are currently testing and piloting the technology. Increased security of PC data and reduced "break/fix" instances are two benefits cited by these early adopters.

One thing to note, however, is that desktop virtualisation is a phrase that encompasses several different types of technology. Dan Kuznetzky, distinguished analyst and founder of Kuznetzky Group, says, “Desktop virtualisation means different things to different suppliers, and this is part of the reason why people are very confused about it.”

First, ‘application virtualisation’ is a system that allows an application to appear to be running on a desktop. It might, in reality, be streamed to the desktop, while running on a server elsewhere.

Related to this is ‘access virtualisation’, a process that allows an application to run on a data centre server, and be accessed using any device whether it’s a tablet, smart phone or desktop PC.

Thirdly is virtual machine (VM) software, which enables the encapsulation of an application – or an entire client environment - in a virtualised system. VMs enable whole desktop environments to run on a gamut of devices, or with multiple versions of the same  environment running on a single desktop environment or local server.

This technique is frequently used to run several different operating systems on one machine, or switch desktop environments between physical machines, enabling workers to roam around whilst still accessing the same desktop.

Desktop virtualisation, or VDI (virtual desktop infrastructure/interface), is a combination of access virtualisation, application virtualisation and VM software. The result is a complete desktop client environment which is encapsulated in a VM, and run either locally, on a workgroup server, or a data centre server. Individuals can access that client environment using a variety of devices, running their workloads back on the server.

Virtual desktop benefits

Kuznetzky said: “This is really useful technology if you can overcome the costs of moving to a more expensive server environment, and it has a lot of powerful benefits.”

Because management is centralised, one major benefit of desktop virtualisation is that IT administrators can test and deploy applications more flexibly, as well as maintaining, patching and securing them from a central console.

Client-side costs are arguably reduced, because the processing, storage and memory burdens are shifted over to the server side, giving the IT department the option of simplifying (and thereby cost-reducing) the desktop estate by moving it more towards thin clients.

The virtual desktop environment can also be served out to the whole range of client devices, from desktops to laptops, tablets and smartphones. This can bring agility to an organisation, enabling it to quickly configure and give secure access to virtualised desktops or specific virtual applications, scaling usage up and down as required.

Another benefit, often overlooked, is that the data is backed up on the server, rather than being held on many client devices, and this aids business continuity and recoverability.

Careful consideration

The one major drawback with desktop virtualisation is that some applications do not lend themselves very well to a virtualised environment. They may have technical workloads that require very large computational resources being available, or make use of very high speed graphics that rely on robust local processing. “Until recently, virtual desktop environments did not deal with those applications very well. They are better off running on a physical machine,” comments Kuznetzky.

Other factors that may contribute to a delay in desktop virtualisation adoption, according to Gartner analyst Terence Cosgrove, are the cost of deployment, off-line and mobile workers, network bandwidth and latency limitations, and a lack of the right IT skill sets. Cosgrove said: "One of the largest barriers to desktop virtualisation is the setup cost, which, in most cases, requires additional server, storage, networking and software licensing."

Kuznetzky concurs that the cost of server memory, processing and storage, relative to the desktop, means that the initial hardware outlay of desktop virtualisation may deter potential adopters. In addition, virtualisation management platforms and tools from the likes of VMware, Microsoft and Citrix, tend to require significant investment, he says.

Kuznetzky concludes that desktop virtualisation needs a large initial investment and the cost savings come in a three to five year period, but the benefits are manifold. “It’s really important to take time to stop and look before you leap,” he advises.