Often the term "VDI" is used to define ArcGIS Desktop/ArcGIS Pro deployed as a virtual application. The challenge is understanding what specific virtualization technology is actually being referenced when using this term since VDI, or "Virtual Desktop Infrastructure", represents just one of several desktop virtualization options. So, the intent of this article is define the options and differentiate what VDI truly means.
ArcGIS Desktop has been delivered virtually for over 20 years using what is referred to as "hosted virtual applications" which includes technologies such as Citrix XenApp (recently renamed to Virtual Apps) and Microsoft Remote Desktop Services (RDS). This approach is referred to as "hosted" because it is being hosted by a singular operating system which users share by initiating individual user sessions. This technology option represents a many-to-one relationship in terms of users and virtual machines. Further, the shared operating system is a server OS, such as Windows 2016 and not a desktop OS, such as Windows 10. Hosted virtual applications provides a means to share a singular server with multiple users and is an attractive option since since each user doesn't require their own dedicated virtual machine. For this approach, system resources are shared including processors, memory, and GPU and there isn't a practical way to assign resources at the individual user session level.
A more recent innovation is to provide individual virtual machines to users as "virtual desktops" where each user accesses a remote desktop deployed with a desktop operating system such as Windows 10. This includes technologies such as Citrix XenDesktop (recently renamed to Virtual Desktops) and VMware Horizon. This approach represents the true meaning of "VDI" as it is defined by a one-to-one relationship between users and virtual machines. Though this approach increases per-user deployment costs, it also provides a more isolated deployment in terms of resources since processors, memory, and GPU resources can be assigned accordingly. The ability to manage GPU resources for the virtual desktops has made this approach an attractive option for ArcGIS Pro which requires a GPU.
So, the next time you hear the term "VDI" used for delivering ArcGIS to users, know that this implies that each user is being presented with their own individual Windows desktop virtual machine with a set of assigned resources as opposed to users accessing a singular server-based virtual machine and sharing it with multiple users, including sharing the server's assigned system resources.
