Virtualization Desktop Infrastructures: The History, Benefits and Drawbacks

Virtualization Desktop Infrastructures

Virtual desktop infrastructures (VDI) is a desktop virtualization approach in which a desktop operating system, typically Microsoft Windows, runs and is managed in a data center. The desktop image is delivered over a network to an endpoint device, which allows the user to interact with the OS and its applications as if they were running locally. The endpoint may be a traditional PC, thin client or a mobile device.

In 2006, Virtualization Desktop Infrastructures (VDIs) began to emerge as an alternative to the server-based computing model used by Citrix and Microsoft Terminal Services. Today, VMware, Citrix and Microsoft all offer their own VDI platforms.

There are two main approaches to VDI: persistent and nonpersistent. Persistent VDI provides each user with his or her own desktop image, which can be customized and saved for future use, much like a traditional physical desktop. Nonpersistent VDI provides a pool of uniform desktops that users can access when needed. Nonpersistent desktops revert to their original state each time the user logs out.

There are four main companies which provide these VDIs: Citrix, VMware, Windows and PCoIP. 


During the early years of computing, there would be two rooms. One was the clean room with large, ceiling high mainframe computers. In the other, rows of terminals or user access. A user would login remotely to the mainframe using a terminal, sharing the system with dozens of other users, each being allocated part of the processor’s time and memory.

Eventually personal computers evolved and each user had their own individual machine at home and one on a desk at work. While this was an unparalleled innovation, there were many challenges for the IT departments that sprung up almost overnight to handle the never ending stream of technical problems. The cost of owning and maintaining a mainframe was replaced with the cost of managing hundreds of personal workstations along with the multitude of software packages and optional hardware devices.

Personal computers became more powerful, evolving into server grade systems. Packed with processing power and speed, the new servers quickly overtook their predecessors, the older massive mainframes. Desktops moved back onto the servers and off the desks of users. Users were given terminals so they could log in remotely to their desktops. Computing technology came full circle: Virtualization was born, again. As server technology became more compact, server farms were cultivated and cloud computing came into existence. Whole office networks could be moved into the cloud and IT departments redeployed and reduced in size.

Benefits of VDI

This approach can have many benefits, depending on the type of Virtualization Desktop Infrastructures deployed. As little actual computing takes place at the endpoint, IT departments may be able to extend the lifespan of otherwise obsolete PCs by repurposing them as VDI clients. And when the time does come to purchase new devices, organizations can buy cheaper, less powerful machines.

Nonpersistent VDI also helps when it comes to management. IT has a minimal number of master images to maintain and secure, which is much simpler than managing a complete desktop for each user.

Because all data lives in the data center, not on the endpoint, there are significant security benefits of VDI. A thief who steals a laptop that uses VDI can’t take any data off the machine, because there is no data on the machine.

Other benefits of VDI include the ability to more easily support remote and mobile workers.

Drawbacks of VDI

The cost savings associated with endpoint hardware can disappear quickly, however, after factoring in IT infrastructure expenses.

Storage in particular can make VDI cost prohibitive. When a desktop runs locally, the operating system, applications, data and settings are all stored on the endpoint. There is no extra storage cost; it’s included in the price of the PC. With persistent VDI, however, the OS, applications, data and settings for every single user must be stored in the data center. Capacity needs, and the cost required to meet them, can quickly balloon out of control.

VDI’s reliance on network connectivity presents another challenge: Users can’t access their virtual desktops without a network connection, and weak connectivity can hinder desktop performance. This problem is especially common with graphics-intensive applications and other software with high processing demands.

In addition, VDI can complicate software licensing and support. Nonpersistent VDI especially causes issues, because some licensing and support agreements do not allow for software to be shared among multiple devices and/or users.

The Future

Session Recording 

Cloud providers popped up overnight to accommodate the transition, but in the haste, some elements were forgotten about.

One of those elements was session recording. Due to the nature of remote desktop access, session recording was not a simple thing to implement. Software was needed to handle the new virtualized architectures and that is where RecordTS comes into the story.

At the very heart of remote access is the terminal server. This is a server that is configured to host user desktops using Microsoft Terminal Services, now known as
Remote Desktop Services or RDS. Users log in remotely to their desktops from either a workstation or terminal using Remote Desktop Connection client software. The client software talks to the server using the Remote Desktop communications protocol or RDP. The user shares the server with other users who are all isolated and protected from each other.

In this scenario, it is possible to insert a recording service between the client and the terminal service in a typical “man-in-the-middle” configuration. In this way, the recording service intercepts all the RDP traffic and makes a copy of the session traffic. The users have no clue this is happening and their sessions are not delayed or noticeably changed in any way.

The session data is stored in a database and can be played back like a video at any time. The recording system is completely configurable and centrally managed. Each component can be located separately to accommodate almost any network configuration. Recording is limited only by the number of desktops a server can realistically host. Literally thousands of servers can be recorded in large scale Environments. It is also possible to record workstations as well as virtual machines in a hosted Environment.

Want to learn more?

Want to learn about a product which will record sessions reliably for a competitive price for Virtualization Desktop Infrastructures? Check out RecordTS at

Read more at our VDI Wiki.