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Sysadmin blog Virtual Desktop Infrastructure (VDI) is a common industry term that has come to mean "all the real work is done on the servers". While VDI technically refers only to VMWare’s implementation of this ideal (now called VMWare View), in practice the term has been expanded to include all similar technologies.

In a VDI setup, the processing, network access and backups – all of it – are handled by various elements of a deeply interconnected data centre. The user connects into a system – virtual machine, terminal services, X or otherwise – and is presented with a graphical interface that is powered by a system other than the one they are using.

The end-user system can be anything: a fat client (such as a traditional desktop or laptop), a thin client, a smartphone, carputer, bit of airport signage or even a digital picture frame.

For the average user, VDI will usually arrive in the form of Microsoft’s Remote Desktop Protocol (RDP), or an extension thereof. RDP is traditionally used by fat clients, with a reasonable chunk of the market occupied by thin clients. 

Since a fat client can do pretty much anything you need it to locally, use of VDI with a fat client is typically for remote access to resources or for security reasons. Very rarely does one use VDI from a fat client for performance reasons.

A thin client is the opposite. Thin clients are locked-down minimalistic systems running cut-down operating systems. They don’t have much in the way of performance to speak of, and they rely on the remote server to do all the heavy lifting. They don’t offer the flexibility of fat clients, but they cost a lot less.

It is zero clients, however, which truly bring us full circle. Harkening back to the days of the mainframe, zero clients are in fact thin clients so thin they don’t have an operating system to do anything locally with at all. Whereas a thin client usually at least has a web browser on it, thin clients are just dumb terminals.

I recently had a chance to play with one; Pano Logic provided me a demo model and the appropriate server software. Promises were made of a true desktop experience from a box about the size of my wallet. I was skeptical.

My test virtual server is modest: a pair of AMD 2378 CPUs with 64GB DDR2 and a pair of 1Gbit NICs. This is the same configuration as the production servers I use with my Wyse thin clients every day.

Overall, I was impressed. They matched my Wyse C90LEWs, and even beat them in video rendering. (I suspect that to be because I am using Wyse’s TCX suite to offload video processing to the Thin Client’s CPU, and the C90s are badly underpowered.)

From a resource load standpoint I was impressed by what I could squeeze out of my existing gear. My rather dated server handled 12 VMs handing DVD-quality video to various different endpoints before I noticed any performance issues. The dual 1Gbit links seemed quite capable of delivering a usable desktop experience to all 12 clients.

Zero clients are functionally worthless for multimedia over a WAN. Then again, so are my thin clients. Pano delivers a usable non-media-enabled desktop over a thready WAN link. Though some assembly is required to in order to get it talking to its management server.

Pano Logic’s zero clients did what they said they would on the tin. They did it well and they did it consistently. Thanks to companies like Pano, thin is the new fat. With legitimate TCO, power consumption and security considerations backing them, zero clients have evolved into credible contenders for your VDI endpoint dollars. ®

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