For companies looking to reduce the cost and complexity of Virtual Desktop Infrastructure (VDI), the attraction of Desktop-as-a-Service (DaaS) is that you can greatly reduce up-front investment. “It’s pay as you go and you only pay for what you need,” says Mark Lockwood, research director at Gartner.
VDI often costs more and delivers less value than expected, warns Mark Lockwood, research director at Gartner. “VDI is complex and it seems like there’s always something extra you have to buy. You have to worry about bursting, you have to worry about the user experience.” With VDI, you have to pay for the infrastructure up front and depreciate it over time; you also have to buy infrastructure for your peak level of usage. “You’re going to spend a ton of money on storage, on compute, on data centers; and if people don’t use it, you still have to pay for that,” Lockwood points out.
“With DaaS, you only buy what you need and you pay for it month to month,” Lockwood says.
Appealing as that might sound, there are several reasons why you can’t treat DaaS as a replacement for VDI. For one thing, you can’t get all of the same features yet. “There are things you can do with on-premises VDI from Citrix or VMware that you can’t do today with a lot of cloud providers,” Lockwood cautions. “Persistent desktops are not available from all providers. You may not be able to do app layering. You may not be able to get a full GPU as an option. You have to be very careful not to assume that you can do with a DaaS provider what you can do with in-house VDI.”
In fact, you need to check carefully what different DaaS providers offer, because the term covers everything from Microsoft’s Azure Remote App to a full desktop that people can use like a PC. Some services offer a full stack, including capacity management and performance monitoring. Some don’t.
As with VDI, nonpersistent desktops suit task workers (in a call center or a retail store, for example) who can work form a standard, shared image. But if you want users to be able to customize their desktop — pinning programs to the Start menu and taskbar, setting up their own signatures in Outlook and generally treating the desktop like their own PCs — you need to look for persistent desktops.
Cost and complexity
“There are perhaps 15 vendors talking about DaaS,” says Lockwood, “and probably none of them have the same definition. They’re different in every way imaginable. The two biggest providers are Amazon Workspaces and VMware with Horizon Air. They don’t even offer you the same operating systems.”
VMware offers Windows 7, 8.1 and 10. Amazon has Windows Server running a Remote Desktop Session so that it looks like the client OS (and only Windows 7 at that), which can cause problems for some software that needs to run on the Windows client.
Because of licensing restrictions, the Windows Server version of DaaS is cheaper. The DaaS provider can sign up for the Microsoft Service Provider License Agreement (SPLA) and also buy a Remote Desktop Service (RDS) Subscriber Access License for each user, which will also be needed for Microsoft software like Office that’s provided by the service, and share the hardware that Windows Server runs on among multiple customers.
For the Windows desktop OS, in most cases you have to use what Microsoft calls Dedicated Outsourcing, running your own volume licenses (with either Software Assurance or Windows Virtual Desktop Access licenses) on dedicated physical servers that the DaaS provider can’t use for any other customers. You’ll also need Client Access Licenses (CALs) for any Microsoft tools that you use to manage the desktops, like System Center, as well as licenses for the software that runs on them.
“SPLA allows the service provider to share a server running Windows among multiple clients. There’s no such thing for the desktop OS,” says Lockwood. “If I go to VMware and say I want a virtual desktop running Windows 7, they have to put me on my own server — and that’s not terribly cost effective.”
Wes Miller, licensing specialist at analyst firm Directions on Microsoft points out several other complications. “Without truly dedicated hardware for each tenant, which is generally antithetical to cloud scale, there is no way to license the Windows desktop OS for use in a server-based desktop ‘as a service’,” he warns. “You bring your own VDA license to the provider offering you dedicated hardware. In essence, it’s ‘your’ hardware.” If the desktops access any of your on-premise systems, you’ll need the relevant CALs for that.
A Microsoft Developer Network (MSDN) subscription does include the right to run a Windows 10 virtual machine on Azure, but that’s only for development and testing, not for production use.
In short, he says, don’t expect to save any money on licensing with DaaS. “At this point, the primary benefit you get from DaaS is that you don’t have to run it, and they may know how to design it for your organization in such a way that you save on hardware compared to your own implementation on-premises. But you won’t really pay less for software.”
The logical vendor to offer Windows 10 DaaS, Lockwood points out, would be Microsoft, especially with Azure Infrastructure-as-a-Service (IaaS) and Office 365 as part of a unified service. For a short time last year, the Microsoft Azure site promised that Microsoft would “enable customers with Windows Enterprise per user to run Windows 10 Current Branch for Business on Azure.” But rather than changing Windows licensing to simplify this or entering the market as a DaaS provider itself, Microsoft recently announced that later this year Citrix customers who’ve bought Windows Software Assurance on a per-user basis will be able to host Windows 10 Enterprise Current Branch for Business images on Azure through XenDesktop VDI — without an extra licensing fee.
Lockwood describes the news as “somewhat significant, but it doesn’t change the fact that Citrix is a partial stack provider. And it doesn’t really tick all the boxes of a real Microsoft all-in-one offering, which could give you everything from IaaS to DaaS with OneDrive and Office 365 included. In reality, this is Microsoft bending their ‘no desktop OS on Azure’ rules for their friends at Citrix, but the question must be asked: Will Microsoft do it themselves next?”
To Miller, “this is the beginning of the news we’ve been expecting to hear,” but he notes that the announcement doesn’t cover costs or the specifics of the virtual desktops, and organizations are still responsible for their own licenses. This might be a significant development for business-ready DaaS, but there are a lot of questions still to ask.
Spec your desktops
It’s important to remember that not all your desktop users will be using simple desktop applications. If they’re doing computer-aided design (CAD), financial modeling, video editing or complex graphics editing, not all DaaS services will offer the right specifications. “Most DaaS providers have a limited catalog of disk space, CPU and memory,” warns Lockwood. “You’ll struggle to find more than two or three providers who can offer you a powerful machine with lots of disk space and high performance GPU — and if they do, it’s expensive.”
That might change later this year when Windows Server 2016 launches — and if the XenDesktop on Azure offering comes after that launch, it could take advantage of new options. The improvements to the RemoteFX support that shares GPUs between client virtual machines (VMs) include support for OpenGL 4.4 and OpenCL 1.1, as well as DirectX 11, and the ability to give each VM dedicated video memory. That means demanding software like Photoshop, ArcGIS and CAD packages will have far better performance — and applications will be able to use the virtual GPU for hardware acceleration, like applying filters in Photoshop.
Windows Server 2016 will also allow hardware pass-through of the GPU using Discrete Device Assignment, so the guest VM will get full access to the graphics card, including using the native graphics driver, which will allow DaaS providers to offer more powerful VMs for compute and visualization. (Azure is using that for the N-series VMs that are currently in preview, but they run Windows Server 2016.) And, again, expect those options to be pricey.
You also need to think about connectivity. If users need to access servers that are in your data center, remember that those will no longer be on the same network as their PCs, so they may notice a delay when opening files or loading data. Check if the DaaS provider charges for data coming in and out of the service. Such costs can add up quickly.
Just because you don’t have the up-front investment in infrastructure doesn’t mean that DaaS is cheap. Lockwood’s research shows that a quarter of Amazon Workspaces implementations had negative ROI after a year, even though it’s less expensive than VMware’s offering. “Discounts might be available for larger customers, but looking at the list price, $40 a month adds up really quickly,” he warns. “In eighteen months you’ll have paid much more than you would have for a physical machine or for VDI. The cost is prohibitive for indefinite use right now.”
Lockwood expects the DaaS market will settle down as it matures, “but the market hasn’t even decided what it is yet.” Even so, there are a handful of situations when DaaS will prove useful. For example, it’s ideal if you need to provide a large number of desktops for a short period of time. Similarly, DaaS can be an inexpensive way to give developers a secondary machine for testing, but you’ll need to make sure they get sufficient performance, otherwise an IaaS service like Azure may be a better choice.
“If you’re acquiring another company and you very quickly need to give them your company’s experience, so they can get to SAP or use your health benefits system,” DaaS is useful, Lockwood suggests.
It’s also well-suited to proof of concept work. “If you’re testing Windows 10, do you want to buy machines so teams can test their apps and re-image them again when they’re done? Is it feasible to buy a whole bunch of infrastructure for VDI that you only need for two months to do app remediation? If you use DaaS for that, you can turn it off once you don’t need it any more, and you don’t even need to pay for it on the weekends.” It’s worth noting that the Citrix Azure service will include AppDNA, Citrix’s application migration tool, to help you move to Windows 10.
Lockwood expects DaaS prices to drop, but even at current prices it will work well for companies with seasonal workers (for example around tax preparation time). “These people need computers for two or three months a year. Is it a good idea to buy two rooms full of laptops that you’re going to ship out to them and then get back, and have to update the anti-virus and re-join them all to the Active Directory because they’re expired, or have VDI infrastructure that’s in use for two months of the year but that you have to depreciate the whole time?”
The appeal of DaaS is that you can give up the burden of deploying, managing and supporting desktops and configuring remote access, without the up-front costs of VDI. But unless you’re certain that you can give all your users good enough performance, pick the scenarios where it’s a good fit, and remember that it doesn’t really remove any licensing headaches.