VDI or session virtualization: which is best for your school?
GUEST COLUMN | by Dave Burton
Managing today’s modern desktops is a costly and time-consuming operational reality for IT departments across educational institutions. Even simple day-to-day maintenance tasks, such as applying patches, upgrading applications, onboarding new users and maintaining security can cause a huge headache for IT. As a result, more and more IT departments from schools all over the world are turning to desktop virtualization as a low cost, powerful alternate technology to traditional PCs.
One size does not fit all, and a smaller organization attempting to fit a solution designed for a large enterprise organization is like fitting a square peg in a round hole.
There are two main types of virtual desktop computing for IT teams to consider: one-to-one desktop virtualization, commonly known as VDI; or, one-to-many — known as session-based desktop virtualization.
VDI vs. Session-Based Desktop Virtualization
VDI uses a hypervisor to run a user’s OS in a virtual machine (VM), decoupling it from the PC host hardware. Typically multiple VMs run on servers in a central data center, isolating the user desktop environment from the physical device and enabling the user to access their virtual desktop from any computer or other access device from any location. Since the computing resources are centralized, management and maintenance is streamlined and easier for IT to deal with.
VDI also requires constant bandwidth and solid network connectivity between the endpoint devices and the back-end servers, so it is not a good fit if offline mobility is required or if schools have slow WAN links to the data center. And if an educational institution plans to implement pooled VDI (the most common approach), then two systems management infrastructures are needed: one for the pooled VDI environment and one for everything else (desktop PCs and notebooks).
Conversely, session-based desktop virtualization allows users to share one virtualized server desktop environment in the form of individual sessions instead of separate operating environments per user. This shared environment can run on servers in a central data center or on a physical PC in a workgroup, computer lab or classroom. A hypervisor is not required for small user environments making it extremely simple to setup and deploy compared to that of a VDI. In the case of larger deployments, the shared desktop environment can run inside a virtual machine on a server. Multiple VMs on multiple servers can scale a deployment to thousands of users.
One advantage of the shared environment is that each user session has a small impact on server resources compared to VDI, and can often support up to 100 users per virtual or physical server. With VDI each user has their own OS, their own set of applications and their own memory and virtual CPU allocation. All of that duplication can dramatically limit the number of users each server may support to as little as one-tenth that of the shared environment. Infrastructure costs will always be lower with the shared desktop model.
A possible disadvantage of the session virtualization approach is that sessions are not completely isolated from one another on the server the way virtual desktops are. The users share the OS and applications installed on the server so standardized environments where users’ needs are similar are a great fit for this approach. With VDI, each user has their own separate OS instance that may be customized when needs vary, for example when users require high-resolution graphics and other CPU-demanding applications.
One Size Does Not Fit All
The critical difference between the two architectures is how the OS is used with the virtual desktops – one-to-one or one-to-many. Although the end-user experience may be very similar for the two approaches, there are big differences for IT. In addition to the impact on server infrastructure and cost, the administration experience is vastly different and it is worthwhile to understand how the differences between the two architectures affect them.
Some virtualization solutions were designed for large enterprise organizations, while others are specifically designed for small- to medium-sized organizations (SMB). Large enterprises often have large IT organizations with a variety of specialized skills and are prepared to take on more complex solutions, while many SMB organizations tend to have small IT teams that must support multiple locations on a tight budget. One size does not fit all, and a smaller organization attempting to fit a solution designed for a large enterprise organization is like fitting a square peg in a round hole.
Educational institutions have fundamentally different requirements when deciding which IT solutions to purchase. They need to allow every student to develop the skills required to succeed in the knowledge economy and access the proper applications, often without the budget and resources to fund or manage a computer for each student. They also need to easily manage the desktops and not rely on teachers or other staff to be IT managers.
What’s more, most students have low computing and user personalization requirements. In this situation where centralized applications are accessed by end users, session virtualization is an optimal solution because it is low cost, energy efficient and requires less computing power in the datacenter. This is also a big plus in computer labs that lack adequate power supply and other related infrastructure.
There are also those users with specialized requirements for high level computing, user personalization and data storage, such as CAD and graphic design. VDI, in conjunction with multimedia capable thin clients, is an excellent solution as VDI can deliver a powerful VM along with storage and software resources to meet these user’s specific needs.
Educational institutions are increasingly turning to desktop virtualization to reduce the cost and resources required today to effectively manage desktops. IT managers must consider their user requirements and their use cases in order to decide which solution fits best for their environment. The architecture for session-based virtualization, in most cases, drives higher efficiency over the VDI architecture because of its use of a single OS and set of applications for multiple users. Using VDI offers an easy way to customize desktops for certain users or groups of users, especially when their computing and graphics needs are very high. Schools should consider deploying VDI when desktop flexibility is more important than immediate cost savings.
Dave Burton has over 20 years of experience in software and technology marketing and currently serves as the VP of global marketing at NComputing. He has a proven track record of leading successful product marketing strategy and related campaigns. He previously served as vice president of U.S. marketing and marketing operations at AppSense, where he contributed to the company’s $100+ million growth.