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Desktop and application virtualization technologies have transformed how IT teams deliver services to business users.
A number of vendors now offer software that supports both desktop and application virtualization. Before choosing one of these systems, IT decision-makers should understand what desktop and app virtualization offer and how each technology can benefit their organizations. They should also familiarize themselves with the various use cases to get a better sense of how they can fully realize the benefits.
Desktop virtualization refers to the process of providing users with desktop services that are abstracted from the underlying host system. Users interact with the desktop's OS and installed applications just like they would on a traditional PC. They can launch applications, open files, resize windows, edit documents and more.
Virtualized desktops can be client based or host based. Client-based virtual desktops run locally on the user's computer and commonly rely on hypervisor software. The hypervisor can host one or more virtual machines (VMs), each supporting its own desktop separate from the underlying system. IT can also deliver virtual desktops by streaming the OS image from a remote server to the user's computer.
With extensive research into virtual desktop and app virtualization products, TechTarget editors focused this series of articles on vendors with considerable current market share who offer both virtual desktop and app virtualization capabilities. Our research included Gartner and TechTarget surveys.
Although some business use cases might call for client-based virtual desktops, IT teams are generally more interested in host-based virtual desktops that run in their data centers and are deliverable over the network. For this approach, they can choose either session-based virtual desktops or VDI.
Under the session-based model, multiple users connect to a common server desktop, with each user running it in their own session. This approach represents the original form of host-based virtualization and is fairly straightforward to implement and maintain, but it comes with a number of limitations, such as users having to share resources.
VDI addresses many of the limitations of session-based virtualization. Under the VDI model, the virtual desktops run on host servers in the data center. Each server is configured with a hypervisor that abstracts the underlying hardware and maintains the VMs where the virtual desktops reside. Most of the desktop-related processing occurs on the host servers.
In addition to the hypervisor, VDI uses at least one remote desktop protocol that transmits the desktop image to the client devices, where agent software receives the remote desktop protocol stream and renders the desktop image on the client device. Users interact directly with that image as though they are working with a locally running desktop.
VDI products also include centralized tools for creating and managing golden images, which generate the virtual desktops, as well as for setting up and maintaining the desktops themselves. In addition, the products include features for securing the desktops and controlling access to them, as well as supporting capabilities such as single sign-on, USB redirection, user profile and policy management, and monitoring and reporting.
The VDI model is the dominating force in desktop virtualization and is often what people are referring to when they use the term virtual desktop.
Application virtualization is the process of delivering individual applications to a client device independently of the local desktop. A server hosts the virtualized application in the data center and delivers it to the client device when the user clicks the application's icon or launches the application in some other way. From the user's perspective, the application works just like a locally installed app.
There are two primary types of virtualized applications: streaming and remote. With streaming, all or part of the application is delivered to the client device when the user launches it. The application then runs on the user's device, just like a locally installed application. Users need to be connected to the network when they download the application, but not when they use the application.
With remote virtualization, the application remains on the host server. The application image is delivered over the network -- often via a remote display protocol -- to the client device, where agent software renders the application image locally. The application image can also be delivered to a virtual desktop. In either case, most of the application-related processing occurs on the host server.
Users interact with the application as though it is installed locally. They can select options, click menus, open dialog boxes, enter text, resize windows and carry out most other tasks. As with virtual desktops, their actions are transmitted back to the server and applied to the running application.
When referring to application virtualization, most individuals are talking about the remote type.
Desktop and application virtualization in the enterprise
Desktop and application virtualization can offer organizations a number of benefits, particularly when it comes to security. The data is hosted in the corporate data center rather than residing on client devices, for example. As a result, IT can centrally manage and control it. Even if a client device is lost or stolen, the data is not exposed.
Virtualization can also contribute to an organization's agility because it is easier to provision or deprovision desktops and applications compared to individual PCs. Administrators can deploy and update hundreds of desktops in a fraction of the time it would take to provision physical desktops.
They can also more easily deploy and update applications, as well as control access to those applications. For example, if they want to prevent specific users from accessing an application, they only need to revoke permissions rather than uninstall the app from individual devices.
In general, desktop and application virtualization simplify maintenance because the majority of the components now reside in the data center, giving administrators more control. Plus, virtualization makes it easier to run legacy applications alongside other applications without conflicts.
Users also benefit because there are fewer disruptions to their workflows, enabling them to stay productive. Even if a device fails, the user can switch to a different device to access resources rather than having to wait for new equipment.
Desktop and application virtualization can also benefit organizations with mobile and geographically dispersed workers. For instance, employees who are traveling can access their desktop or business apps from anywhere they have an internet connection. In some circumstances, they can even access resources from their mobile devices, particularly less complex virtual applications.
Virtualization also has the potential to help companies save money. Users don't need state-of-the-art PCs because all the processing is done on the server. In some cases, organizations can use thin clients rather than full-blown PCs.
Because virtualization minimizes downtime and maintenance windows, users can stay more productive, helping the organization maintain a competitive edge. This simplified management can also lead to cost savings, as can the potential for more efficient hardware and software usage.
IT must be careful when evaluating the costs of desktop and application virtualization. The initial capital expenditures can be pricey, as can the expertise required to deploy and maintain these systems. An organization might also need to beef up its network to handle the increased loads, which can be taxed especially hard by graphics-intensive applications or apps that process large quantities of data.
App virtualization can introduce other challenges, as well. For example, not all applications are suitable for virtualization -- such as the graphically intense ones. Virtual applications can also complicate the use of peripheral devices, whether the devices connect to the client computer or to the network.
Virtualization use cases
Despite the challenges that come with desktop and application virtualization, many organizations can benefit from one or both of these technologies. For example, a medical facility might turn to virtualization to help protect patient records, virtualizing both desktops and applications and delivering them based on the user's role. A nurse making patient rounds might use virtualized applications to record a patient's vital signs, while a receptionist might use them to accept a copayment.
IT benefits by being able to better control security, utilize resources, reduce application conflicts and minimize administrative overhead. In addition, by using virtual applications in conjunction with virtual desktops, IT can reduce the amount of overall desktop maintenance.