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There's a BIG problem with Microsoft's VDI rules

Dedication, that's what you need

If you’re talking virtual desktop infrastructure (or VDI) there are a few options – VMware Horizon View, Microsoft Remote Desktop Services, even smaller players like 2X Software – but chances are you’re going to plump for the biggest hitter, the company which has been doing it for the longest. You guessed it, I’m talking about Citrix.

From its early days delivering multi-user access technologies for OS/2 and Windows NT, Citrix Systems’ core offering has always been server-based.

From WinFrame and MetaFrame to Presentation Server and latterly Citrix XenApp, Citrix has been delivering desktop-like application access on Windows Server operating systems.

Usually this works well, but occasionally there can be compromises in dressing up a server OS like a desktop one (and hoping nobody trips over the cracks). So when Citrix released XenDesktop it was seen as the answer to all of these issues.

Citrix has changed its core focus from XenApp to XenDesktop in recent years, and even tried (unsuccessfully) to kill off XenApp, only to face a backlash and reinstate it as a sub-product of the now dominant XenDesktop.

There is, however, an outside factor preventing the world at large from switching en masse to XenDesktop, and that ultimately led to the backlash that forced Citrix to take the noose from around XenApp’s neck. It is ... Microsoft licensing.

If you want to operate XenDesktop (other VDI technologies are available) in a corporate environment, you will encounter no issues around licensing, particularly if you have a Select Licence Agreement with Microsoft for easy access to desktop licences.

If you purchased Software Assurance on top of your Select Licences, you automatically receive an entitlement to utilise your local desktop licences in a dedicated hosted environment.

That’s great news for sysadmins in internal environments – any user licences in play automatically transfer in a 1:1 relationship with software used on your virtual desktop infrastructure – so all that hardware humming away in your server room, used to facilitate remote access or business continuity; it’s all covered from an end-user licensing standpoint.

What happens if you’re not big enough for a Select Licence with Software Assurance, though? Microsoft has you covered there, too. You can purchase a Virtual Desktop Access licence, which entitles a user with a licensed version of a Windows on their local machine use a single instance of a Windows desktop operating system on a VDI server, in that same 1:1 ratio.

So as long as your local licence is nice and legal, and you purchase the extra VDA license for about $100 per year, then you’re covered in the virtual environment.

What if you’re responsible for virtual desktop provision to more than one organisation; if you’re part of a body with multiple discrete arms, or even a managed service provider? Unfortunately, that makes you incompatible with Microsoft’s Virtual Desktop Access licensing – at least, not without jumping through some serious hardware hoops first.

There is no Service Provider License Agreement for Microsoft’s VDA, and for a Virtual Desktop Access license to be above board, the remote system must be run entirely on dedicated hardware.

The terms and conditions of the VDA license states: “Hosters need to ensure they isolate the hardware and other resources for each company. Any hardware running an instance of Microsoft software (OS or application) must be dedicated to a single customer.”

You can’t even be sneaky with virtualisation. The aforementioned T&Cs are wrapped up so tightly that the word “hardware” is operative at every step. That means physical hosts have to be dedicated; virtual machines aren’t enough. The VDA agreement even goes so far to state that a SAN must be dedicated per customer, if said storage is going to be used to host Microsoft software being delivered under Virtual Desktop Access licences.

Servers are one thing, but the notion of an individual SAN per customer is ludicrous and instantly nixes any business model that attempts to deliver hosted VDI on Citrix’s preferred technology, XenDesktop.

So, until a day comes that these licensing issues are addressed we’ll be left making the best of Microsoft’s bad job; trying to get Windows Server to look and behave like a desktop operating system under XenApp – all that just to remain compliant with Microsoft’s licensing. ®


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