Microsoft is pushing desktop virtualisation as a way of making Windows 7 play nicely with old applications, especially those written for Windows XP. So now that the technology has been "blessed" by Microsoft, can the industry brace for a desktop virtualisation boom? Probably not, most experts agree.

That said, though, there will likely be an uptick in the acceptance of desktop virtualisation, for a couple of reasons. First, more vendors are offering Virtual Desktop Infrastructures (VDI), which give each end user a private "desktop." VDI uses the same kind of hypervisors that allow many virtual machines to run on a single physical host. But rather than running five- or ten-server VMs on one physical server, VDI can run 50 PC operating systems, each of which serves a single end user.

The other big change is support for peripherals, multimedia and other web- and PC-focused technologies. These have been inaccessible for users of shared-image terminal services types of systems, that is traditional desktop virtualisation, but nowadays most users won't do without them.

"Improvements in the user experience are really a big deal in making desktop virtualisation more acceptable," says Andi Mann, an analyst with Enterprise Management Associates.

Giving end users all the benefits and all the capabilities they'd have on standalone machines, including the ability to add or update their own browser plugins, media players and other "extraneous" software, could overcome most of the objections by business units that have kept virtual desktops out of the mainstream user base, Mann says.

Extending the life of an old PC

Another element that may make virtual desktops far more popular is the unwillingness of some companies to upgrade their PC hardware enough to support migrations to Windows 7, according to Chris Wolf, infrastructure analyst at The Burton Group.

Implementing Windows 7 requires upgrading hardware, updating custom built software, training end users and updating the security on PCs with the new OS. That process can be so expensive and disruptive that many companies are asking consultants like The Burton Group to evaluate whether it makes sense to leave end users on their present hardware and upgrade them by running Windows 7 as part of a virtual desktop connection, Wolf explains.

Connecting end users to a new OS on the server can more than double the life of an ageing PC, while still giving end users all the power and support for new software and new technology they want, according to Peter Graves, CIO of Independent Bank.

Because about 90% of his bank's users already use shared session virtual desktops from Citrix Systems, adding the other 10% is no great leap once the technology supports the software customisation and peripherals they need, Graves says.

The same is not true of most companies, many of which have little history or understanding of virtual desktops and are just getting used to virtual servers, cloud computing and cost- and labour-saving IT tactics, Mann says.

This may explain why desktop virtualisation has been around for at least a decade, but it has yet to take off. IT managers have told analysts and pollsters that they're ready to adopt virtual desktops but have not yet made the leap.

"All the surveys we and others have done of end users showed a tremendous interest in desktop virtualisation that just hasn't happened yet in the marketplace," Mann says. "We've been looking for a sharp inflection in sales of virtual desktops for three years", but it hasn't taken place.

A survey of end user companies that Enterprise Management Associates released in September shows the top three barriers to desktop virtualisation are all human factors, based either on users' ignorance of the technology or politics about who has control over it.

Windows 7's role

Banks, hospitals, schools, government agencies and other organisations that have either very tight budgets or restrictive operating regulations have made up the bulk of Citrix' and Wyse Technology's installed base for years.

Other companies, which have resisted terminal services-based virtual desktops as too clunky, too restrictive and too offputting to independent minded workers make up a constituency of what vendors now hope will be a rush to new desktop virtualisation products, Burton Group's Wolf says.

There's nothing that requires all those potential virtual desktops to run on Windows, let alone Windows 7, Wolf acknowledges. While running virtual Windows 7 desktops would be cheaper than the real thing, it's still not as cheap as the virtual XP desktops companies may already be running.

Still, the appeal is there for some customers. Virtualising a Windows 7 migration gives IT a lot more control by keeping the whole process inside the data centre and by reducing the hardware and support costs as well, Wolf says.

That might make two big migrations more attractive than just one, at least that's what Microsoft, Citrix and a host of third-party developers are hoping, he says.

Microsoft's dilemma

For its part, Microsoft seems to be playing both sides of the issue. The vendor is clearly supporting desktop virtualisation, but is leery of anything that would threaten the primacy of the standalone PC as the main business computing platform.

Even Microsoft's main desktop virtualisation product manager doesn't sound comfortable with the idea that most or all of a major company's PCs could be virtualised.

"We expect to see a significant amount of deployment [of virtual desktops] on Windows 7 from CIOs looking for reduced costs in deploying applications on Windows 7," says Scott Woodgate, the director of Windows product management who is leading development of Microsoft's desktop virtualisation technology.

While Microsoft is "excited to have an offering" in the virtual desktop market, the company believes customers "should virtualise for the right reasons, for the flexibility it offers, not just focus on the potential cost savings," Woodgate says.

Windows 7 itself should save money compared to Vista for its better management, security and stability as well as because it takes up less disk space than Vista, he says. This in turn could save costs in VDI implementations that involve hundreds or thousands of instances of the OS running in separate VMs, Woodgate explains.

On the negative side, Woodgate says, VDI implementations are more complex to configure than more standard PC-based networks. VDI networks require administrators to create virtual machines, permissions and policies governing how the VMs behave and the images from which VMs are launched, in addition to configuring and managing a standard PC network.

Some users agree with Woodgate's assessment about complexity. George Thornton, network operations manager for Texas' Montgomery Independent School District, and Landon Winburn, Citrix administrator for the University of Texas Medical Branch, a medical school, said that planning virtual desktop rollouts can be intimidating to IT groups that are just getting started.

Figuring out which of several delivery methods is most effective for specific types of users is difficult, as is creating just a few "golden" OS images most users can launch as "their" desktop, rather than try to keep a different one for each user, Thornton says.

Savings can be tricky to calculate

Further, Microsoft's Woodgate worries that companies can overestimate their potential cost savings with virtual desktops because they don't add the cost of gearing up the data centre to support it.

"You're replacing the hard drive of a laptop, which is about the cheapest memory there is, with space in a Storage Area Network, which is about the most expensive memory there is," Woodgate adds.

On that point, Woodgate and Winburn disagree. Server- or SAN-based storage is secure, backed up, cheaper to maintain and far more rarely lost, broken or abused than a laptop, Winburn says.

And, Thornton says, even looking just at hardware costs, virtual desktops saved his organization about $100 (£60) per machine. The district wound up using the free XenServer rather than VMware's vSphere on the servers as was the original plan.

"With a thin client and Linux OS on it, half a gig of RAM, a little Atom processor, licence for XenDesktop, plus the cost of a server divided by 30, we figured we could get 30 VMs per server, we came up with about $550 per unit," Thornton explains. "Compare that to $650 to $700 for a regular PC. Thin clients have no moving parts, they're built to resist heat. We figure they'll last eight or 10 years, compared to three or four Gartner recommends for a PC. That raises the savings even more."

In zeroing in on cost as a crucial element in the virtualisation decision process, Thornton and Winburn agree with the majority of IT shops. Indeed, Mann's survey at EMA showed that three quarters of companies interested in desktop virtualisation primarily wanted to save on hardware and administration costs, and half expected to save on software.

That contrasts with server-based desktop virtualisation, in which 70% of respondents said flexibility and agility, the ability to add or reduce computing power, the ability to launch as many "new" virtual PCs as necessary at a moment's notice and the ability to give users access to "their" PC image or files no matter where they work, was the main reason to switch.

Schools' big savings

As one of the fastest growing districts in the country, the Montgomery Independent School District standardised two of the three schools it opened this fall on Citrix virtual desktops. In addition to saving $100 per unit and more than doubling the lifespan of his PCs, Thornton says there were other savings. "To support the other 2,000 PCs in the district I have five people and they never get to sit down all day long. For the 700 [new virtual desktops] we have one person and he only works on it about an hour or two per day."

All of the district's 700 virtual desktops use XenDesktop on the client, connecting to XenServer servers on the back end. All but around 15% use shared session connections. The rest, mostly in computer labs and in classes that need to use Adobe Photoshop, computer assisted design software or other resource-intensive applications, have VDI setups that give them a dedicated virtual machine for additional power.

It's not just education in Texas that's tapping the power of virtualization. At the University of Texas Medical Branch, the support, hardware and network load are different depending on what type of virtual desktop is involved, Winburn says. But any kind of virtual desktop delivers a far more efficient use of IT resources than putting all the power of a PC on every user's desk, he explains.

"The big difference is that you don't have to support the endpoint, just the user settings and the network and servers," Winburn says. "I could put five or six PCs on a T1 at a clinic somewhere and people are going to complain that Outlook is slow to open, or it takes too long for browsing. I could throw 30 or 40 [Citrix thin clients] on that connection sharing one desktop image back in the data centre, and they run like a champ."

Desktop virtualisation options are expanding

Traditional, terminal services-based virtual desktops allow dozens or hundreds of end users to sign on to a single operating system and set of applications, all running on a backend server. That keeps costs very low, but limits or eliminates the ability of individual users to configure their own environments. It also keeps them from viewing bandwidth-intensive video, Flash animation or other multimedia, whether on the web or on controlled internal applications. This happens because most desktop virtualisation software doesn't have a mechanism to support it, Mann says.

That's changing with newer versions of the server software from both Citrix and Wyse. Citrix' recently released XenDesktop 4 supports not only multimedia, but also USB connections at the client side. The result is that end users can plug in peripherals like printers, scanners and memory sticks or even fans, lights and desktop toys if they like, Mann says.

VMware, long the leader in the virtual server market, plans to release similar support in its VMware View VDI products early in 2010.

But even then it will trail Citrix in the number of delivery methods it offers for virtual desktops and the breadth of products tailored to specific problems, like the Citrix branch repeater that slashes the amount of bandwidth required for remote sessions of the notoriously chatty Exchange server, Mann explains.

Further, Citrix' HPX technology eliminates one of the few barriers to using a virtual PC just like a real one, according to Graves. HPX allows users of VDI-based virtual desktops to use web-based multimedia and to plug USB devices into their local machines, even if the software operating the peripherals and the browser is running in a data centre somewhere, Graves says.

With that addition, the bank can expand its centralised virtual desktop support and delay buying new PCs, reducing the $400,000 (£250,000) it currently spends on new hardware, Graves says.

It's not clear yet whether the 10% of Independent Bank's 1,200 employees who don't already use virtual desktops will be able to make the leap to VDI, according to Ben Kohn, senior systems architect for the bank.

Kohn has been supervising the bank's tests of Citrix USB and multimedia support, connecting non-virtualised users to VDI-based virtual desktops. The tests have gone well and most users like being able to use the newest operating systems and the speed and power they get from a dedicated VM running on a bank server, rather than the same applications running on an aging PC.

Another benefit: Because the "desktop" each user accesses sits on a server in the data centre that IT patches and upgrades, end users have had fewer problems from viruses, malware and misconfigured applications, Kohn says.

If the bank ends up migrating those users permanently to VDI-based virtual desktops, they should continue to see top performance, because the bank upgrades servers faster than it would refresh PCs, Kohn explains. The decision about whether to migrate those users or more widely adopt the latest version of XenDesktop won't be made until its tests are complete, however, he says.

No rush to virtualise, with or without Windows 7

Given all the variables that are still up in the air, there probably won't be an explosion of Windows 7-inspired desktop virtualisation in Corporate America anytime soon, according to Michael Rose, client hardware analyst at IDC. Traditional shared session virtual desktops will remain popular in their traditional niches, whether with Windows 7 or other OSes, Rose says. It will take time, however, even for companies eager to use newer VDI systems to add the network and server capacity they require.

"It would involve significant spending in the data centre to accommodate adding vast numbers of users on virtual machines," he said. "Desktop virtualisation will continue largely to be a tactical technology, though as it moves more toward the endpoint device, handhelds and other nontraditional hardware, there's more of a possibility it will become very common."

Bottom line: Windows 7 could be a catalyst for some additional virtualisation, given improvements in the technology that have helped mitigate concerns over relative performance, perceived lack of personalisation and other issues. However, this technology isn't seamlessly stitched together yet. Administrators still have to master the nuances and best practices, and few will want to make the transition at the same time they convert over to Windows 7.