When it comes to virtual desktop infrastructure, administrators have a lot of choices. You may have wondered about the differences between VDI software options, remote display protocols or all the licenses out there. In this series, we tackle some of the biggest head-scratchers facing VDI admins to help you get things straight.
Figuring out Microsoft's rules for licensing virtual desktops is no easy task. The confusion around Microsoft VDI licensing stems from two reasons. First, there are many ways to implement virtual desktop infrastructure (VDI), making licensing different for each organization. Second, the vendor has so many different products -- and licenses for those technologies -- that it can barely keep track of itself.
That means you, the VDI admin, need to keep track of virtual desktop licensing requirements. For Windows desktops, you should understand Software Assurance, Virtual Desktop Access and -- as BYOD initiatives grow -- the Companion Device License. Let's get this straight:
What is Software Assurance?
Software
Assurance (SA) licensing provides Windows desktop customers with technical support, training
vouchers, home-use rights and other benefits. But you have to pre-pay a percentage of the license
price to account for future software upgrades. SA makes the most sense for organizations buying in
bulk. Otherwise, it may be too expensive.
Application virtualization comparison
How cloud-hosted desktops differ: Comparing VDI, DaaS
Comparing remote display protocols
Microsoft overhauled its virtual desktop licensing in 2010 because customers weren't happy with the per-device model. To run Windows virtual desktops, you needed the Virtual Enterprise Centralized Desktop (VECD) license, and having Software Assurance on top of that made virtualization a bit cheaper.
Still, the expensive VDI licensing program led Microsoft to add roaming rights and release the Virtual Desktop Access (VDA) license, which is $100 per year, per device. If you have Software Assurance, VDA rights are included, so you don't need any extra licenses to run VDI. However, non-SA customers and customers that run thin clients need the VDA.
Microsoft VDI licensing cuts costs only for SA customers
If your organization runs thin clients and can't afford Software Assurance, Microsoft
VDI licensing hits hard. Microsoft has said that customers using thin clients aren't included
under the virtual
desktop access rights in SA because thin clients don't require a client OS. Still, you may save
money in the long run by implementing virtual desktops rather than physical desktops because of
energy and hardware cost reductions.
How client hypervisors factor in -- or don't
Microsoft isn't clear on its client
hypervisor licensing rules. Software Assurance customers can use client hypervisors to run up
to four Windows environments on a corporate desktop that's licensed with SA. For non-SA customers,
the company doesn't provide specific regulations. However, Microsoft will release its own Hyper-V
Client hypervisor with Windows 8, so its licensing policy should become clearer.
Virtual desktop licensing costs could hinder adoption
It took a while for Microsoft to come around to desktop virtualization, because with customers
using VDI, that could cut into its profits from desktop management and hardware. For many
businesses, the vendor's licensing policies still prevent VDI
adoption. That's especially the case if you don't have SA, because you must purchase SA with
the original desktop license and can't add it to older computers.
Microsoft virtual desktop licensing guide
Microsoft FAQ on VDI licensing
Four ways Microsoft is screwing desktop virtualization
VDI project pitfalls: Licensing and more
If you use thin clients, look into cheaper ways to license your Windows virtual desktops -- with or without the VDA. Third parties offer thin clients that come with SA or sell clients that you have to buy VDA for. Manufacturers could even offer Certificate of Authority licenses to help thin client customers get around the VDA.
Another alternative is to run Windows Server VMs instead of desktop VMs. That would require you to buy Remote Desktop Services client access licenses, however, so it may not be much cheaper than just buying the VDA.
Windows 8 VDI licensing includes BYOD
Microsoft updated its Windows
8 VDI licensing to include rules for bring your own device (BYOD). It added the Companion
Device License (CDL), which organizations need to purchase for each non-Windows device that
accesses a corporate virtual desktop. The CDL allows employees to access VDI-based desktops from up
to four other personally owned devices under one license.
How the CDL will or won't help you
If you don't already have VDA licenses for mobile
devices that access virtual desktops in your office, you'll have to buy the Companion
Device License for every tablet or smartphone. For many organizations, this adds more licenses
to keep track of and more cost. Plus, it doesn't matter whether the company or the user owns the
device. Everything must be licensed.
Does Windows RT get a free ride from VDI licensing?
Windows
RT devices, which run ARM-based processors, include VDA rights. That might be a better
alternative than VDA for companies that supply phones or tablets to their employees.
Employer-bought devices aren't covered under the CDL, so they'll need full VDA licensing, Office
licensing and possibly other client access licenses. Still, Microsoft's language around using
Windows RT devices to access VDI isn't clear whether it's the same
access as the CDL provides.
24 Sep 2012