The difference between a VDI and an RDS desktop may be small for users, but for IT, the decision of how to host its virtual desktops is extremely important.
Virtual applications and desktops play a key role in the modern enterprise, but before IT can get started, it must consider VDI vs. RDS and each approach's strengths and weaknesses.
Both RDS and VDI are methods of storing and delivering virtualized desktops and applications, but they differ in a few ways. Generally speaking, VDI provides more control and customization, while RDS minimizes storage and overhead costs. Organizations thinking about VDI vs. RDS should consider compatibility, licensing and more during the decision-making process.
Virtual desktop infrastructure uses and features
VDI allows IT to deliver individual virtual desktops and applications to user endpoints over a secure corporate network as a centralized server hosts desktop instances in a data center. Organizations that rely on VDI for application and desktop virtualization often manage the entire back-end infrastructure in-house.
VDI allows IT to customize the infrastructure to their users' needs. For example, organizations that run graphics-intensive virtual applications can make more significant GPU investments than other organizations. IT has the option to host virtual desktops as persistent or nonpersistent -- the former saves users' customizations, while the latter stores desktops as a clean slate of identical machines -- and virtual applications with different methods, including virtual application streaming and layering.
IT must allocate virtual resources such as memory and CPU with VDI. If organizations run into issues with resource allocation, they can configure servers in their infrastructure to use resources more efficiently by pooling them for multiple OSes to use as needed.
Advantages of VDI
One major consideration in the VDI vs. RDS debate is that with VDI, IT can virtualize any applications that are not compatible with the user's OS and deliver the virtual apps separately to avoid any compatibility issues.
For organizations with VDI, persistent desktops provide the security and management benefits of virtual desktops, while also allowing users to maintain a desktop that is exclusively their own. Nonpersistent VDI distributes desktops randomly to users, so personalization is more difficult to accomplish. IT can use these two options in tandem as needed, which allows more flexibility in the desktop hosting model.
With VDI, organizations aren't limited to Windows, so they have more flexibility to deliver different types of virtual desktops for different use cases. VDI can also better support more resource-intensive use cases such as 3D design with customized desktop images and extra resources allocated for the virtual desktops.
Each user has its own server with VDI, as opposed to RDS users accessing virtual desktops from the same server, so VDI's approach offers a higher level of security. VDI also allows organizations to customize the virtual desktops and infrastructure to meet compliance standards specific to highly regulated industries such as healthcare and banking.
Disadvantages of VDI
The hands-on approach IT must take to manage VDI can turn into a time-consuming task. For example, building the back-end infrastructure that makes up VDI requires a significant resource investment. Additionally, once the back-end systems are in place, VDI scale-up and scale-down are manual tasks for IT administrators.
Organizations can personalize nonpersistent desktops by establishing user profiles, but IT must still find a way to store all the user profile data. IT can store the profiles on the endpoint devices or in network storage, but each of these options comes with drawbacks.
If IT stores the user profiles on the endpoints, users must have devices with enough storage capacity to house the data, which is often not the case with low-cost thin clients. If IT pros store the user profiles on network storage, they are negating some of the storage savings that nonpersistent VDI provides.
Microsoft licenses its Office and Office 365 products on a per-user basis, which can cause problems for nonpersistent VDI. Persistent desktops belong to specific users, so they allow IT to assign licenses to users. With nonpersistent desktops, however, multiple users can access the same desktops. Software licenses typically stick with the same user and desktop, so when users access a different desktop with each logon, the traditional model of licensing doesn't work.
IT can address this licensing confusion with Microsoft Office 365 ProPlus, which assigns the license to the desktop rather than the user. As a result, IT can allocate Microsoft Office licensing for the number of users that might be working on the desktops at any given time. But this approach puts more of a management burden on IT.
Remote Desktop Services uses and features
Remote Desktop Services is a Windows Server protocol that delivers session-based desktops. With RDS, users access a shared OS and desktop image on a server where their virtual resources come from one pool that encompasses all users. In the same way the VDI can host multiple desktop images, Microsoft Windows Server, which hosts RDS, can host different instances of the machines that RDS clones for the end users.
Users can connect to RDS servers via any secure network that can establish a remote desktop connection -- users aren't required to connect with a VPN or corporate network. RDS provides users with a clean Windows desktop, any preconfigured business applications and the necessary compute resources to perform work tasks.
RDS shifts the burden of building and customizing infrastructure away from the organization, which can be helpful for organizations that don't have the resources to build up their own VDI.
Advantages of RDS
One example of this is how RDS takes the issue of licensing off IT's plate entirely. An RDS subscription includes a temporary client access license for each desktop session. Because RDS licensing is temporary, there is no device limit, so users have remote access to Microsoft Office on any of their endpoints, which could include a desktop computer or a mobile device. This is ideal for users accessing virtual desktops from various devices or for users sharing a desktop.
Like any business technology, the choice between VDI vs. RDS will come down to the organization's use cases, resources, existing virtualization technologies and the skill set of IT administrators.
While RDS offers more simplicity compared to VDI, there is still some room for customization to improve the user experience. Organizations that subscribe to RDS can virtualize and host applications on their own infrastructure, but they must rely on Microsoft Application Virtualization (App-V) to do so. IT must work within the App-V hosting guidelines. Once IT uploads an application to App-V, it can deploy it to users just as it would any other virtual application.
RDS allows for some customization with the personal session desktop, which Microsoft added to RDS in Windows Server 2016. This is IT's best bet to provide RDS users with personalized desktops. Personal session desktops provide individual users with the same desktop whenever they log on. Personal session desktops also give IT the option to retain administrative privileges over the desktop or allow users to work as their own desktop administrators.
Disadvantages of RDS
Virtual desktop administrators may run into issues with applications that aren't compatible with the cookie-cutter RDS desktop. This can create performance issues and block access to certain applications across all desktops, which IT cannot easily fix. To work around such issues, IT pros using RDS should create silos that separate the storage of each application, preventing one application's issues from causing problems with other applications.
Typically, RDS offers limited personalization because all the users access the same OS and applications during their desktop sessions. Additionally, RDS cannot run any OS that isn't hosted on Windows Server. Any use cases that require virtual macOS machines, for example, would require a different approach. IT administrators can connect macOS devices to RDS, but they cannot use RDS to deliver macOS to their managed endpoints.
Choosing VDI vs. RDS
Like any business technology, the choice between VDI vs. RDS will come down to the organization's use cases, resources, existing virtualization technologies and the skill set of IT administrators. For example, if an organization made the significant upfront investment of building on-premises VDI and doesn't have the resources -- labor and capital -- to make an overhaul to all its servers, then the incumbent VDI may be a better option. However, some organizations with existing VDI may find that it isn't a great fit for their business anymore. If they have the resources, it may be worthwhile to leave their old VDI behind and transition to RDS.
For organizations with no existing investments in VDI, the decision is a bit more straightforward. Organizations with the need for quick scale-up or scale-down, pools of noncustomized virtual desktop, or exclusively Windows operating system access should be able to work with RDS. Organizations with complex business applications that IT must virtualize, a wide range of user types that each require unique desktop images, and the resources to build their own custom back-end infrastructure are more likely to find that VDI meets their needs.
