james kahn’s scratchpad

Edit: After recent developments in the industry and some re-thinking on my part about the benefits of VDI, I’ve changed my tune on this. VDI is relevant for a significant segment of the market that SBC isn’t. Primary benefits of VDI? User empowerment, desktop customisation and simpler maintenance.

Virtual Desktop Infrastructure - or VDI for short - is one of the latest phenomenons striking the IT industry. If you’re tuned in to the standard IT industry rags, Citrix, and Virtualisation resources, VDI seems to be hailed as the next revolution in desktop delivery. However, that isn’t the case.

For those that aren’t aware, the concept of VDI refers to centrally hosting desktop virtual machines - usually Windows XP or Vista - on a number of servers stored in the data centre. End-users would then use thin-client devices or low-end PCs to connect to and work from these virtualised PCs. The actual operating system and data are all stored centrally in the data centre.

The advantages of doing this include:

• Your data is centralised, so it’s easy to back up and keep it under control.
• You can take advantage of some of the availability features of virtualisation solutions to (perhaps) provide greater uptime.
• Users can have a full “PC” environment when using only a thin client.
• It’s much more hardware and budget-friendly than the terrible blade-PC solutions from HP and IBM. (On a side note: Why anybody would go for a blade PC solution blows my mind. They must have very good sales people).

While at first glance VDI appears to be a compelling and potentially beneficial architecture for running your business on - the truth is a little different. VDI would be a great technology if it existed in a vacuum. Unfortunately, it doesn’t, and there are a number of solutions that already solve many of the problems that VDI does, and they do it in a more cost-effective, manageable way. If you’re investigating VDI, there are two other technologies you should be considering that will probably provide a better solution in the end: Citrix Presentation Server/Terminal Services, or a Managed Desktop Environment.

A Citrix Presentation Server environment involves setting up a farm of Windows Server-based terminal servers, and hosting your user’s applications and desktop environment on these in a classic multi-user fashion. Depending on the applications and server configuration, you can usually get between 50 and 80 users on each standard specification server. To compare Presentation Server with VDI:

• Your data is centralised with either solution.
• Presentation Server/Terminal Services usually has a greater user density, resulting in a higher number of users per physical server, and reduced licensing costs for operating systems when compared to VDI.
• Both have built-in load balancing/availability characteristics, although VDI’s is more seamless if hosted under VMware.
• Presentation Server provides a management platform to manage your user farm, whereas VDI management tools do not solve the platform and application management problems (more on this later).
• While you can give people free reign with VDI, you generally want your Presentation Servers to be controlled to provide a stable user environment.
• Both have inadequacies and are unable to smoothly provide rich, graphically intensive applications.

In short, Presentation Server is generally a cheaper, more manageable solution than VDI for the main VDI use case - hosting the data and applications centrally.

A Managed Desktop Environment is a controlled desktop platform hosted on standard desktop computers. A tool like Altiris’ Client Management Suite, Microsoft SMS/SCCM, or Microsoft System Center Essentials (for smaller environments) provides a standard operating system build, standard application installation packages, configuration management and remote support capabilities. You can give your users as much or as little freedom over their own computers as you like, based on your requirements. When compared with VDI:

• VDI centralises the workstation and data environment to the datacenter; a Managed Desktop Environment doesn’t centralise the workstation platform, but can centralise or replicate the data.
• There aren’t any built in availability characteristics in a single workstation, but if it fails only one user is down for a short time while another machine is automatically built.
• Costs can be similar to VDI, when all hardware and software is accounted for, including capable, thin clients for the VDI solution.
• A Managed Desktop Environment performs well with all types of applications, including graphically intensive ones.

A Managed Desktop Environment needs a management platform (e.g. Microsoft SMS), which has a cost associated with it. However, in order to provide a standard operating platform, a VDI solution also needs a management platform. VDI only addresses the question of where the operating system is run from, and not the desktop environment management system.

Most businesses - I would go as far as to say 99% of the businesses I deal with - would reap more benefit at lower cost from a Citrix Presentation Server solution or Managed Desktop Environment for their core operating environment than with VDI.

VDI is a very neat technology, and it does have it’s place. There are some very specific situations where you might use VDI, for example:

• An outsourced developer (in say, India), that needs to use a Windows desktop environment where they can install applications, don’t use graphically intensive applications, and where you want to protect the data by storing it centrally; and,
• Other development “sandbox” style environments.

VDI, like many other technologies, will find it’s niche in the long term as a point solution, but won’t become a major game changer.

Thanks to BrianMadden.com for their series of articles on VDI.

Edit: Please note that I’m not saying VDI has no uses. I believe that it’s useful in it’s niche, but is not anything to get terribly excited about.