Virtual desktop infrastructure (VDI) is one of those technologies that has never quite become mainstream. But a combination of changes in costs, the rise of Bring Your Own Device (BYOD) schemes, and the increasing use of public and private clouds means that the virtual desktop's time may finally have come.
The conventional, enterprise-based approach to VDI is offered by virtualization vendors such as VMware (with VMware View) and Citrix (with Citrix XenDesktop), or by other vendors such as Pano Logic and Quest Software who offer VDI systems which sit on top of the hypervisors provided by these virtualization vendors.
VDI involves purchasing a large amount of server and storage hardware on which to run virtual machines - the virtual desktops which are accessed using standard PCs, thin clients, mobile devices such as tablets or smartphones or, in Pano Logic's case, a driverless, processor-less "zero client" hardware device into which a mouse, screen and keyboard are plugged. The principal benefits of VDI are that it is easier, and therefore less costly, to manage applications and operating systems centrally, and that it offers better security, as data stays within the data center and can be backed up from there. Anti-malware, intrusion prevention and other measures can be also be more easily implemented centrally.
The principal drawback to enterprise VDI implementation is capital costs - specifically the very high upfront costs of the server and particularly storage hardware required, and to a lesser extent the VDI software and desktop hardware.
But Simon Bramfitt, principal analyst at Entelechy Associates, said these upfront costs have fallen dramatically over the last two years or so, and since the end of last year he has seen many projects moving from the pilot stage into production. "With Citrix and VMware we are seeing deployments of 10,000 seats plus. Companies have definitely stopped talking about VDI and started doing it."
Gunnar Berger, a research director at Gartner, thinks that VDI has become more attractive because the cost of managing conventional PCs has been going up over the last few years rather than because the upfront cost of VDI has been falling, pointing out that while a single IT staffer could support an average of 357 devices in 2006, increased complexity meant that in 2011 this number had fallen to 285 devices, according to Gartner figures. "Virtual desktop implementations are rarely about capex savings. It's all about lower opex."
He added that 40% to 60% of the cost of most virtual desktop implementations is for storage hardware. "Storage and technology vendors are working very hard to address this, and if storage costs fall below 40%, then virtual desktops will be a lower capex play as well as a lower opex play. If that happens virtual desktops will be a slam dunk - a no-brainer because cheaper always wins."
But he points out that implementing VDI is not easy, because IT staff that manage large numbers of PCs don’t necessarily have the skills to manage VDI environments. And even if staffers are experienced in server virtualization, that won't necessarily help because desktop virtualization is very different to server virtualization, he warned.
Cost is clearly a very important factor in VDI adoption, but another factor that is driving adoption appears to be mobility, and more specifically the number of devices that employees want to use to access their desktops, according to Simon Bramfitt. He says the average user now has over three devices (such as a traditional office desktop machine, laptop, smartphone, iPad or other tablet, and home computer), and this is a significant increase over a few years ago. "There is clearly a need for user centric (rather than device centric) management, and this makes VDI very attractive," he said. "The need for mobility and the growing use of BYOD initiatives has certainly helped VDI adoption."
Desktop as a Service (DaaS) Competes with VDI
But alongside enterprise-based VDI, there is also an alternative: desktop as a service (DaaS) offerings delivered from the cloud. One of the biggest names in DaaS is Massachusetts -based Desktone, and as well as offering its own service, companies like Rackspace, NaviSite, Netelligent, Dell and tuCloud offer DaaS based on Desktone's platform. Citrix also announced the intention to move in to this space at its Synergy conference in May with its Project Avalon. This will allow its XenDesktop VDI product to run on Apache CloudStack and Amazon Web Services in the cloud.
DaaS is meant to do everything that traditional VDI does, but with the benefit of no upfront capital costs at all. It is also designed to allow companies to scale up their virtual desktop requirements very rapidly - something that can't be done easily with conventional VDI - and enables companies to try out virtual desktops in different departments to see if the approach works. "You can prove the use case for virtual desktops very quickly using DaaS," said Danny Allan, Desktone's chief technology officer. "You don’t need to spend months doing an assessment of who could benefit from it," he said.
He added that bandwidth and latency problems can be issues when it comes to implementing a DaaS solution, but said that the VDI protocols that have been developed work very well in most cases. Desktone's platform runs on top of VMware, Citrix and Microsoft based virtualization, and works with specialized protocols such as Citrix's HDX and FlexCast, VMware's PCoIP and Microsoft's RDP.
Cloud service providers are likely to push DaaS to potential customers over the coming months, Allan believes, because they see themselves as shopping malls. Desktop as a service is the "anchor tenant" which they can use to attract more business, Allan believes. "After they start to provide your desktops, they can offer to handle SharePoint, or your storage, and so on," Allan said.
But there are technological reasons why DaaS is not the "lower capex and opex slam dunk" that it appears to be, and that conventional VDI might become, Gartner's Gunnar Berger believes. Peripherals such as those that rely on a fast USB 2.0 connection will never be able to communicate quickly with a service provider's data center, he pointed out. But more importantly, he says that with many applications the user experience suffers too much. With enterprise VDI desktops move closer to applications in the data center, which may lead to better performance than is achievable with desktop PCs. But with DaaS, desktops move further away from corporate applications in the data center, and that is bound to make performance worse, he says.
Arguably the main barrier to DaaS is not technological at all, but legal. "Right now the biggest challenge for DaaS is licensing," Berger said. The issue is a complex one, and revolves around the fact the Microsoft does not offer a Service Provider Licensing Agreement for Windows 7. This doesn't prevent DaaS service providers from offering Windows desktops, but it does make it more complicated and costly than it otherwise would be, and involves dedicating the software and the hardware it runs on to individual clients. (The average price of an enterprise desktop run from Desktone's platform is $35 per month.)
DaaS may also not be suitable despite this in situations where industry regulations oblige companies to keep their - or their customers' - data in house, or where they feel - rightly or wrongly - that they need to for security reasons, he added.
For a combination of these reasons, Simon Bramfitt says that many companies are wary about choosing a DaaS solution while enterprise VDI solutions are still developing. "We see lots of companies choosing cloud hosted desktops, but only as a bridging infrastructure. About 2% see DaaS as the long-term solution, but the vast majority want to see how VDI turns out and see the cloud as a safe interim solution."
The conclusion then is that the virtual desktops are not quite ready to replace physical desktops in the way that virtual servers are rapidly replacing physical servers in organizations of all sizes. The benefits of virtual desktops are certainly real though, and now it’s a matter of waiting for upfront costs to come down and licensing issues to be resolved.