The cloud's not ready for desktop virtualisation

In the past, virtualisation has always been about servers: improving server utilisation, enabling server consolidation and simplifying server management.

Now, VMware, Microsoft, Citrix and a host of start-ups want to use virtualisation to solve a different set of problems: easing desktop deployment, centralising desktop management and providing portability of the user's desktop experience.

This is desktop virtualisation and the big three virtualisation players and a host of venture capitalists are betting that it is going to be one of the next major trends in enterprise IT.

"I think it's a huge opportunity," said VMware chief executive Paul Maritz in his keynote address at VMworld 2008. "It's as big as VMware is today."

Maritz said he's been hearing a simple message from IT leaders: "We need to get control of the desktop." As a result, Maritz said he sees desktop virtualisation taking hold over the next 12 to 24 months.

However, there are technical challenges that could inhibit that kind of growth.

The way desktop virtualisation typically works is that the PCs that employees use to get their work done are virtualised and hosted in the datacentre. The user can then access their virtual computer from a bare-bones terminal station, saving the money and complexity of deploying full PCs.

Alternatively, a user can access the virtual PC from a traditional desktop or laptop machine, even an older one that is underpowered, since the processing power is done on the servers in the datacentre and only images of the active screen are sent over the network and processed locally. A diagram of this configuration is shown below.

Credit: VMware

The challenge with this type of topology is that it puts a lot more pressure on the network. Server-based desktop virtualisation demands a network with low latency and a symmetrical connection of at least 5Mbps. That's not a problem for most LANs but, as soon as you bring a WAN connection into the equation, latency and bandwidth become an issue. That's important because around 70 percent of employees work in an office other than the company headquarters.

Companies like Teradici, with its PC-over-IP system, have done a great job of improving the technology for running PCs hosted in a datacentre. They have successfully made the user experience of the virtual desktop feel just like a normal desktop, with all the same apps and accessories. Nevertheless, even companies like Teradici will admit that their technology is completely dependent on a low-latency, high-bandwidth network connection.

One of the most interesting things VMware did at VMworld 2008 was to hitch its wagon to cloud computing — one of the hottest topics and most overused phrases of the year. A Cisco executive at VMworld even joked that, at the moment, any start-up that uses the phrase 'cloud computing' in its business plan is guaranteed to get funding from venture capitalists in Silicon Valley.

VMware told IT professionals that they could use its software to build their own internal cloud. And, of course, this also has implications for the larger cloud, since the eventual goal with desktop virtualisation is to make a person's desktop available to them from almost any computer and over virtually any internet connection.

In the meantime, there are a few desktop virtualisation solutions that take a different approach, focusing on local processing and much better online/offline synchronisation. The most notable are Kidaro and MokaFive.

Kidaro — which was bought by Microsoft in March 2008 and will be released in 2009 as Enterprise Desktop Virtualization — provides a seamless experience in which a virtualised app runs from the datacentre, but all the processing is done on the local machine and the app itself even looks like any other app. These apps can even dial their own VPN connection, if needed.

MokaFive also uses local processing for its desktop virtualisation program, but it accomplishes it with a USB thumb drive (or any other USB storage device).

MokaFive separates the user state from the system state and can back up both of them to its site, or you can set it up to back up to your own server. The end result is that the users have a highly available system that can always be accessed by simply plugging in the mass-storage device where their user state is saved.

Bottom line
Cloud computing demands a level of uptime and performance that simply are not universally possible right now — even in highly-developed nations — and won't be for at least a decade. You can only have that type of connectivity in small pockets, such as the LAN at the corporate headquarters.

In those places, desktop virtualisation will have a chance to thrive. It could be especially useful in environments where there are lots of shared systems and a robust network, such as healthcare and manufacturing.

However, in environments with lots of knowledge workers, the Kidaro and MokaFive solutions make a lot more sense because they take advantage of the current infrastructure and build on it to produce a more usable system that works with today's diverse networks.