I often get engaged to help customers choose between the proper zero/thin/thick clients on the market for their particular VDI solution. One topic of conversation that often comes up is USB connectivity, redirection and speed.

Before the discussion can be held in full, it is important to clarify the difference between how Microsoft’s current Remote Desktop Protocol (RDP) handles USB disk drives and how VMware View using PCoIP handles the same situation.

When using RDP to a establish a remote connection, assuming Drives and/or PnP Devices that I plug in later is enabled, the USB disk drive will show up in a similar fashion to how mapped network drives are displayed.

In the above screen shot you will notice that my USB drive is showing up as, “F on JLangone-LPT” as opposed to a specific drive letter.

What does this mean?

This means that the USB drive is working more like a network share, so the quicker the overall connection parameters, the quicker data will move to and from the USB drive. As a matter of fact, if I drop to a command prompt, I don’t even see the, “F:\” drive. However, if I type net use it is displayed (again more like a network share).

For example, if our user plugs her USB drive into a laptop that only supports USB v1.1 and establishes an RDP connection, data can only move off the USB drive to the local machine at 1.1 speeds before it’s then sent over the wire to the local session. A USB v2.0 device plugging into a laptop that supports 2.0 will move data at a quicker rate.

Sounds good, what’s the drawback?

This is not proper USB redirection. I repeat, this is not proper USB redirection. While connected to RDP, if we pull up the Disk Management console, we won’t see the disk at all.

This also means that RDP is very limited in what USB devices it can present to the virtual desktop; it’s primarily limited to USB disk drives and printers. Would a USB scanner work out of the box without the use of any other third-party solution when using RDP? Negative.

Well does PCoIP actually show the USB disk drive as a drive?

It sure does; because it’s doing actual USB redirection.

Here I am connecting up my USB disk drive. The virtual desktop treats it as if I just plugged in the actual device into the virtual desktop. Some drivers are installed and my device is ready for use.

If I fire up Disk Management, you will notice that Disk 4 is displayed, which is my USB disk drive. I could change the letter, format it, do whatever I desire. Try that with RDP!

Great, then I’ll use PCoIP and call it a day.

Your beloved USB scanner should work when using PCoIP with your VMware View-powered virtual desktop. Unfortunately, Teradici has limited PCoIP to 1.1 speeds at this time.

So, when working with customers to help them decide, it’s important to understand what peripherals will be connecting to the virtual desktop, reasons for using PCoIP versus RDP (need the graphic experience of PCoIP), and then setting the proper end user expectation.