Putting the desktop into the cloud

When many IT departments talk about the cloud, they're thinking about big boxes. Cloud computing evokes images of banks of virtualised servers, all running enterprise applications on a small number of physical boxes. But there is another side to cloud computing: the desktop.

Desktop virtualisation is a trickier thing to manage than clouds of enterprise applications, but the idea is tempting. Desktop PCs are notoriously difficult to manage. They represent large capital expenditures, because the hardware must be refreshed at least every three years. They are prone to problems, caused by user error. And every time a helpdesk operative has to go out and service one, it costs the company money.

Instead, some advocate putting desktop PCs into the cloud along with everything else. Instead of an expensive 'fat' PC sitting on the desktop, a user may access a thin client, with little more than a simple processor, display unit, keyboard and mouse. Some don't even have hard drives.

The advantages here are legion. The equipment is cheaper to buy, and lasts longer. It doesn't consume as much power, which has an effect on power consumption throughout a large company.

It also carries management benefits. The operating system is stored centrally in a cloud computing environment, rather than out on the desktop. This makes it easier to control. In a traditional computing environment, an employee using a laptop might take it everywhere with her, but may not connect to the office system all the time. That makes it difficult for the IT department to maintain and patch that operating system. And if she runs into trouble with a missing operating system file or corrupted registry entry while in Singapore, she is out of luck.

If she accesses a cloud-based operating system while on the road, then that system stays within the IT department's control. Whenever a new patch or operating system build is deployed, the IT department can do it centrally. The next time she logs in, everything will be taken care of, and she will never find herself trying to use a corrupted or compromised operating system.

This all sounds attractive, but it is far from simple. There are different kinds of desktop integration, each with different ramifications for a private cloud infrastructure.

One of the most controversial is virtual desktop integration (VDI). This model provides the most functionality and flexibility, but it is also the most expensive. It involves giving a single virtual desktop to each user. No one else uses that operating system or its files. It's your operating system, in the cloud, and you don't have to share it with anyone. This model provides sterling performance, but it also requires the most computing resources.

The other option is session virtualisation. In this model, multiple users share a single operating system and its applications. The infrastructure only saves individual user sessions (their current status on the operating system). Microsoft Windows used to offer this facility using a feature called Terminal Services. Since Windows server 2008 launched, it has been updated and renamed Remote Desktop Services. Session virtualisation is a good option for IT departments that want to streamline management.

There are other kinds of desktop virtualisation that leave the operating system on the computer, but draw other elements into the cloud, such as the user's profile, or some applications. But for real desktop in the cloud, these are the primary methods.

If you're going to virtualise the desktop, there are many issues to consider. For example, the users play an important part in the process. They will need convincing that desktop virtualisation will benefit them, without degrading their overall experience.

Some desktop applications will also be bad candidates for desktop virtualisation - especially those with specific hardware requirements, such as graphics-intensive programs. And then, of course, there is the cloud infrastructure itself to consider. Will it be able to support the high levels of network activity and storage access that desktop operating systems will need in the cloud?

Think about all of these things before wresting control of the desktop away from your users, and weigh up the potential challenges against the benefits of centralising your desktop access. The potential rewards are huge - but one bad move could bring the wrath of your users crashing down on your IT department.