Virtual desktops

“Desktop virtualisation is a very different beast and should not be treated as simple enhancements to the server strategy,” says Natalie Lambert, principal analyst at Forrester Research. “The drivers are entirely different and the environment will present new challenges to those experienced with server virtualisation.”

For instance, desktop virtualisation doesn't offer the near-immediate cost benefits many cite with virtual server rollouts. And while virtual servers present new security and management challenges, many argue that in the desktop realm, virtualisation improves security and manageability for IT departments. In addition, the sheer numbers involved can be strikingly different.

What is the promise of desktop virtualisation? “Employees increasingly want access to applications and data from anywhere or from any device. While this adds to workforce productivity, it can create complexity and higher pressures on cost control for IT departments. Additionally, as hardware theft rises, securing laptop and desktop PCs requires significant resources. Therefore, companies are increasingly turning to virtualisation as the answer to their desktop challenges,” says Xavier, Windows Business Group Manager, Microsoft Gulf.

Desktop virtualisation involves decoupling the different computing layers and storing some or all of them in a data center. Through virtualisation, employees can access their applications and data very safely over a network, minimizing the risk of data loss. On the IT side, virtualisation accelerates deployment of new capabilities without needing to acquire new hardware and configure components. It also helps reduce application testing requirements and compatibility issues and simplifies disaster recovery and compliance.

According to industry experts and IT pros, there are some similarities and many differences between virtual servers and virtual desktops. Here we highlight key factors that could help avoid major headaches when moving virtualisation to the desktop.

Complexity intensified

Most IT departments at enterprise companies have exponentially more desktops to support than servers, virtual or otherwise. The sheer volume of desktops should be one of the first criteria IT managers consider when making a move to a virtual platform.

With more than one billion PCs in the world, there's a huge opportunity for virtualisation, but “all the requirements of the PC world need to be maintained as you migrate into the data center,” says Mark Margevicius, vice president and research director at Gartner. “The desktop realm represents a lot more moving parts, considering all the uniqueness that happens on a PC needs to be maintained.”

Server virtualisation teams are unlikely to be responsible for the desktop infrastructure, beyond the servers that host the virtualisation platforms. That means desktop groups need to rethink patch management, software distribution and other functions when applying them to a centralized system rather than a slew of disparate desktops.

“Desktop teams know how to manage 100,000 machines so the practices and policies are completely different. In the virtual realm the desktops come back to the server environment but cannot be thought of in the same terms,” Forrester's Lambert says.

Double the cost, half the ROI

While server virtualisation virtually guarantees a speedy ROI, desktop virtualisation can be cost-prohibitive to start and deliver a somewhat less immediate and difficult-to-quantify return on the substantial investment.

Analysts estimate choosing virtual desktops can cost 150% to 250% more than traditional PCs — and that's just for the direct cost of acquiring the technology. Savvy IT managers realize when pricing out a project they need to also calculate indirect costs.

“Depending on how cost is calculated, one could simply take the cost of the desktop OS and include the additional cost of the software enabling desktop virtualisation (Vmview/XenDesktop, etc.) which sell from anywhere between 99$ to 150$/ concurrent user. A more synthetic view would be to take into consideration the cost of hardware by adding the extra costs related to the data center infrastructure like server/storage,” says Yan Bergeron, Category Manager for Workstations and Thin Client, PSG, HP Middle East.

Putting a price to desktop virtualisation is difficult because it's specific to each customer situation, as you can leverage on existing hardware and software already in place. There are also many different level of virtualisation such as a single application virtualisation to a full OS.

“Desktop virtualisation is a lot like hybrid cars. No one disputes the value and they love the idea, but it is just too expensive to write a check and pay a lot when the traditional version is cheaper and already paid for,” Gartner's Margevicius says.

Don't forget network, storage

IT managers must also look closely at network and storage requirements in their virtual desktop environment because if they don't, what is already an expensive endeavor will become too costly to continue deploying.

Storage is a lesson already learned by server teams deploying virtualisation, says Andi Mann, vice president of research at Enterprise Management Associates. For that reason, desktop groups should depend upon the experience of their peers when considering storage. For instance, 5,000 desktops each with a 60-gigabit drive built-in could prove to be cost exorbitant. But by bringing those storage requirements back to the data center, Mann says, via thin provisioning and data deduplication, desktop teams will lessen their costs and optimize resources.

“Storage management is one of the biggest concerns about desktop virtualisation. A lot of resources can be wasted if not managed properly,” Mann says.

He adds that the network is another area of concern, thought it's not typically on desktop managers' minds. While Gigabit Ethernet is a standard for data centers, it has yet to be widely deployed to the desktop.

Determining network capacity and understanding if an upgrade is in order could help IT managers decide on virtual desktops, Seitz says. “The network needs to be able to handle aggregate traffic from many desktops to one location in the data center, so an upgrade from 100MB Ethernet to Gigabit might be necessary,” he says.

Are bare-metal hypervisors better than hosted desktops?

The biggest development in the desktop virtualisation arena has been the emergence of bare-metal hypervisors, a type of local desktop Virtualisation that installs the hypervisor on top of the PC's operating system. “They are expected to provide better security than Type 2 hypervisors, because the bare-metal type runs independently of the client operating system and deliver better performance than hosted desktops, because applications run on the local client instead of a remote server. Microsoft bare-metal hypervisor is the Microsoft Hyper-V Server 2008 that was built using the Windows hypervisor and other components, including base kernel and driver technologies. Microsoft Hyper-V Server 2008 is a great choice for customers who want a basic and simplified virtualisation solution for consolidating servers as well as for development and test environments,” says Xavier.