Virtual Desktops in the Classroom


I got a great question into the Ask the Architect email bag that I thought it would be great to share and potentially create a good discussion. Let’s say you are in a classroom setting where students are only in the class for 4 weeks and then after those 4 weeks, you need to reset all desktops back to a base image. Before desktop virtualization, you could use Ghost or other tools. But could we use desktop virtualization for this? Does it make sense?

As this environment is already using the local, physical desktops, I’m assuming the desktops have adequate resources, so let’s continue to use them by using the Streamed VHD FlexCast model. For those unfamiliar with Streamed VHD, I’ve provided a very rough drawing

Because the desktops have enough resources, we want to use those for computing power, thus reducing the need to buy a lot of servers in the data center. All we need is a Provisioning Services server. The classroom image (1 per classroom or 1 for all classrooms) will be streamed across the network to each physical desktop.

The unique thing with this use case is that students need to be able to modify the desktops and then when the 4 weeks class ends, those modifications are thrown away. With Provisioning Services, you simply use the Differential Disks, which will store the changes (write cache or delta disk) on the Provisioning Services server. So the PVS server will be holding the differential disks for all of the classroom desktops.

When the 4 week class is over, you simply remove the differencing disks and the desktops reset to the base state, ready for a new class. Pretty slick.

What do you need to make this work?

  1. One or two PVS servers (for redundancy) with enough storage to hold the disk image and the differential disks. You will want these disks to be fast as well to reduce latency
  2. At least 100Mbps switched to each endpoint
  3. Endpoints that are similar in hardware configuration (the more identical they are, the easier this will be)
  4. Network boot capabilities on the desktops and configured within the environment (DHCP, PXE, TFTP)

Note: If you want to see how to configure the difference disk or to see it in action, take a look at this CitrixTV Video.

Daniel – Lead Architect
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4 thoughts on “Virtual Desktops in the Classroom”

  1. Great idea, although you are still up against a hardware specific image though, and this assumes all computers are equal, and the IT department has the time to create an image for this devices. In many cases I think a lot of people will go with vm hosted because the implementation is easier and quicker, and the images and infrastructure are already there. I’m not sure if others have seen the same, but once the endpoint hardware configuration can be written out of the equation, it’s hard to go back. Thoughts?

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  2. You point on the hardware is correct, the more different each desktop is, the more difficult the STreamed VHD solution becomes. However, what if they don’t have any desktop virtualization yet? To do the hosted VDI desktop model would require a lot of server hardware and design, but going streamed just required PVS. I know most classroom settings I’ve seen standardized their hardware, or bought it all at the same time. This will overcome the biggest issue with STreamed VHD, hardware standardization.

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  3. PVS is the most under-utilized and least-understood technology! I advocate this model of “Desktop Virtualization” with every education institution I come in contact with.

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