While preparing this series of blogs on virtual desktops, it occurs to me that virtual desktop, like all technologies, has its own set of acronyms and terminology that may not be commonplace for everyone, but are necessary to define and understand. With that in mind, this first blog is actually a condensed glossary of acronyms and terms relevant to virtual desktop solutions. My next blog will outline the steps necessary to roll out a virtual desktop infrastructure in your environment… not surprisingly, the terms below will be used frequently:
VDI: Acronym for Virtual Desktop Infrastructure; this is the entire environment required to run virtual desktops including servers, storage, endpoints (thin or thick clients), software, and images.
Hardware Thin Client: A hardware device that replaces a traditional desktop or laptop. Hardware thin clients have few or no moving parts and provide ports for peripheral device connections (keyboards, mouse, monitor, etc.)
Connection Broker: The connection broker maintains a list of available virtual desktops, and when a client makes a request it provides the client with the connection information (including authentication) for the appropriate virtual desktop.
Base Image: A base image is the minimum desktop and application requirements for a set group of users. This would be used as a starting point for all full desktop deployments. A base image will allow you to minimize the applications that need to be managed when deploying desktops. When you know that office, a PDF reader, and your main enterprise application will be used by every employee, why would you want to manage them separately?
Full Clone: A full clone is an exact replica of a virtual machine at a point in time. This clone will take the same storage and performance requirements of the original image. The full clones are normally used when you have group of desktops that will be assigned to a specific user group, and they allow you to install applications or any other desktop customization. Full clones are your most resource-intensive group of virtual desktops that can be deployed and should be used only when absolutely needed.
Replica Disk: The replica disk is a full clone of the base image that is used to take snapshots of the base image for the creation of linked clones. This is normally a read-only copy of the base image. If you created linked clones you will take a snapshot of the replica disk and users will work off of the snapshot. This consumes the full CPU and memory resources of the base image, but only for changes done by the user.
Linked Clone: A linked clone is a snapshot of a replica disk that is accessed by users. This snapshot only consumes the storage resources as it is used. A full sized clone would take the same amount of storage as the original. This will allow you to save upwards of 90% of the storage needed for a full desktop clone pool.
Virtualized applications: Virtualized applications are applications that have been packaged to run independently of the operating system. Virtualized applications can be presented to desktop pools or shared via file share. These virtualized applications would be used to augment a base image. The application that might be used by one department in addition to the standard apps could be virtualized to ease management.
Persistent vs. Non-Persistent: A persistent pool would mean that a user would always access the same virtual desktop; this is most commonly used when a user has access to make changes to their system, for instance, administrative rights or application installs. In a non-persistent or floating pool, the user could receive any desktop in the pool. Floating pools are most often used in office environments or call centers. When any user logs in they could get any machine in the pool and their profile would migrate with the user.
User Profile: The user profile can include all the settings that a user would change, to include the desktop background, files and icons on the desktop, and any settings assigned through application installation. User profiles are part of a user’s active directory profile and are used regardless of a physical or virtual desktop.