Ever since the introduction of Microsoft Azure Virtual Desktop (AVD), also formerly known as Windows Virtual Desktop (WVD), we often get asked what the main differences between this solution and Virtual Desktop Infrastructure (VDI) are.
While a variety of vendors have implementations of Virtual Desktop Infrastructure (VDI), we are going to compare Microsoft’s VDI solution (Azure Virtual Desktop) to Citrix Virtual Apps and Desktops (CVAD) as this is what people commonly refer to when they say VDI.
Overview
Desktop virtualization typically takes place in a client/server environment where applications and data remain on a remote server, while a local thin client only receives keyboard, video, and mouse (KVM) information. It usually involves the server hosting multiple instances of desktop operating system instances by running a hypervisor, an architecture originally derived from a Multiwin engine developed by Citrix and licensed by Microsoft. This design is generally known as VDI, although many people use this term to refer to any desktop virtualization implementation.
AVD is directly integrated into Microsoft Azure Resource Manager, enabling easier automation with simpler management. On the other hand, CVAD offers a broader range of options since it’s been in the virtualization market longer. Important points of comparison between these two solutions include flexibility, image management, application delivery, and cost.
AVD
Windows Virtual Desktop (WVD) was an Azure-based service for virtualizing Microsoft’s Windows operating systems (OSs) that provided virtualized applications and desktops in the cloud, primarily for enterprise users. Microsoft announced WVD in 2018 and provided a public preview of it in March 2019, before making it generally available by September 2019. WVD was rebranded as AVD in June 2021.
CVAD
Citrix released a multi-user OS named WinFrame in 1995, which included the MultiWin engine as its core component. This product went through multiple name changes from 1998 to 2008, at which point it was known as XenApp based on Citrix’s acquisition of Xensource. Citrix rebranded XenApp as CVAD in 2018 to reflect its use of virtualization in providing remote desktops.
Flexibility
AVD uses a simpler architecture that runs both the control and data planes as Azure host services, meaning that customers only need to operate the VMs. Citrix customers can also use CVAD against multiple cloud platforms simultaneously, while also enabling business continuity and disaster recovery. AVD only supports Azure, but it has no known limits on its scalability.
CVAD can integrate with many on-premises platforms like Citrix Hypervisor and VMware vSphere as well as cloud platforms such as Amazon Web Services (AWS), Google Cloud, and Microsoft Azure. It also offers greater flexibility than AVD in terms of deployment options, especially with respect to Active Directory (AD) structures, traffic steering, and double-hop support.
Image Management
AVD doesn’t currently have its own ability to manage images, but administrators do have other means of obtaining this capability since AVD is native to Azure. For example, they can use Azure Image Builder (AIB) for this purpose, which allows admins to automate the creation of Azure VM images by using configuration files. AVD can’t automatically provision VM based on a new image because Image Builder isn’t natively integrated to AVD. However, AIB is a generic Azure service, so admins can combine it with other services to build an image.
Admins can facilitate image management with CVAD by using both Machine Creation Services (MCS) and Provisioning Services (PS). MCS uses storage to clone and provision VMs, while PS uses network-based image streaming to provision VMs.
Application Delivery
The delivery of application functionality for AVD is comparatively limited when considering it by itself. However, the Azure ecosystem includes other capabilities that users can combine with AVD to access additional applications. For example, Azure AD Application Proxy allows access to web applications that are part of Azure AD. The only disadvantage of this method of application delivery is that users must access AVD and these applications from two different portals.
CVAD provides access to other OSs like Linux in addition to the web-based applications integrated into their gateway components. This capability also provides remote access to computers via their remote PC functionality. In addition, CVAD includes always-on virtual private network (VPN) capabilities for applications and services. Azure offers this capability as well, although separately from CVAD itself.
Cost
AVD uses Azure’s own scaling model to charge customers only for the resources they use, making this cost an operational expenditure. CVAD generally requires customers to make a substantial capital investment for on-premises servers and licensing for Citrix’s own software as well as other software required by the servers such as Windows Server. As a result, CVAD is much more expensive than AVD, especially when it comes to upfront costs.
Summary
Microsoft’s VDI offering has come a long way, especially now that it’s native to Azure. AVD users will likely see additional enhancements and features in the near future, but AVD is only a small part of Azure’s ecosystem. As a result, larger VDI vendors like Citrix will maintain the advantage in functionality and user experience for the time being. AVD’s significantly lower cost will appeal more to smaller businesses, especially those who are new to implementing VDI.
Stay tuned for another breakdown of the differences between Microsoft Azure Virtual Desktop and Windows 365. While Windows 365 uses a lot of AVD-based technology, the differences are vast.
