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Musings on an Eight-year VDI Journey

By Didier Contis, Director Technology Services / College of Engineering, Georgia Institute of Technology


Didier Contis, Director Technology Services / College of Engineering, Georgia Institute of Technology

Located in Atlanta, Georgia Institute of Technology is a leading research university. Its College of Engineering (CoE) is consistently ranked among the country’s top 10 engineering schools and among the top in the world.

Our virtual desktop infrastructure (VDI) journey started early 2007, when we were looking to give our students better 24/7 access to software, needed for their coursework. This was motivated by an increasingly mobile and geographically dispersed student population, a growing number of Mac users, difficulties in licensing engineering applications for personal machines, space constraints resulting from enrollment growth, and the overall inefficiency of computer labs.

In the eight years since then, we’ve faced our share of challenges, but we’ve found VDI to be a valuable tool for students. Below are some reflections and lessons learned while building our Virtual Lab (VLab) environment using Citrix XenDesktop.

The value of partnerships

Starting as a “little bet,” the project evolved into a federated condominium infrastructure to accommodate other partner academic units. Settlers (and now planners ) have since replaced pioneers , as our university’s central IT office progressively took over the infrastructure to transitionVLab into a commodity service.

Cost-saving was never our motivation

Early on, VDI was often associated with increased return on investment and lower total cost of ownership. We never subscribed to this school of thought. So why did we then invest in something we considered more expensive and complex? To improve access to the tools our students needed. We decided higher cost and complexity were worthwhile if they meant greater agility and flexibility.

Start with BYOD before converting your computer labs to thin clients

Initially we designed VLab as a complementary service to brick-and-mortar computer labs. Our end-users (students) were willing to accept a less than perfect experience in exchange for more conveniences, such as the ability to work remotely from the comfort of their dorm rooms. This enabled us to learn and improve the service progressively. If you “upgrade” a computer lab with thin clients, then, that what has been deployed must be better than what it replaced, allowing little margin for error.

Thin client as the university cable box

Our students, based on their class enrollment, can access multiple specialized virtual desktop environments from their personal devices or via thin clients deployed across campus. Treating thin clients as a “cable box” has improved computer labs space usage, and having to schedule a class in a specific computer lab due to limited software availability is a thing of the past.

However, unanticipated challenges have emerged along the way, such as realizing that we underestimated the diversity of USB devices having to be connected via thin clients. USB-based data acquisition devices or Bluetooth dongles to remotely control robots do not always work out of the box.

Never underestimate the impact of small design decisions on the overall perceived service value

We found out that setting session disconnected timeout too high guaranteed the premature exhaustion of available virtual desktops as students rarely log off, instead simply closing their session windows and thus creating “zombie sessions”. A value too low diminished the service value by limiting students’ ability to reconnect at night and pick up where they left off on class assignments.

Similarly, a maximum session time set too low limits for a student’s ability to run assigned homework simulations, while a value too high invited graduate students to use VLab as secondary computational systems.

Be prepared for the unexpected

Students’ ability to access VLab from anywhere on campus quickly raised the question of “which printer should I use to print my assignment” while sitting on the lawn. Browser caches and user-installed applications (like Dropbox) have caused random log-on issues.

“VDI empowers our students to focus more on their work instead of worrying about accessing software”

Our help-desk technicians compiled support tales while helping students with occasional Citrix receiver installation problems. Some wished they had a bio-hazard suit before working on laptops; others became interested in learning new foreign languages after dealing with so many international keyboard layouts.

Access from anywhere, anytime, and any devices

Our students have certainly demonstrated this concept. Support stafflearned to ask the right questions: Where are you connecting from and what kind of device are you using? What type of Internet connection do you have? Maybe this was motivated by support tickets from students trying to watch Silverlight Video over a 3G wireless connection in Australia or “scoring” an early Google CR-48 Chrome OS laptop before any IT people on campus.

We educated more vendors than we were educated by

We met numerous salespeople over the years from different areas (network/storage/software). Invariably, many hours were spent explaining how VDI in higher education differs from a “standard” enterprise deployment. An on-demand instructional environment does not have the same infrastructure requirement and impact as dedicated 8x5 VDI sessions for staff. Providing access to complex and computationally intensive engineering is not the same as providing access to Microsoft Office and a browser. (We have over 20 gold images between 100GB and 200GB.)

VLab will always be blamed first

The dog-ate-my-homework excuse has now been replaced by VLab-ate-my-assignment. Over time, we lost some control over how and for what VLab was used, as the service became a default answer to many use cases. This has forced us to learn about the service-provider mentality. What can go wrong when hundreds of students are trying to take a final exam without you being forewarned?

GPU acceleration

Being the largest engineering college in the U.S means thousands of students are enrolled in Aerospace, Civil and Mechanical engineering. From bleeding edge to mature technology, weintroduced GPU acceleration into our environment using the NVIDIA GRID technology in the year 2012. The increased heat / power consumption makes us wonder if we will need to borrow at some point self-contained/cooled racks from our HPC group.


While DaaS is on our radar, we are focused on adding Linux-based virtual desktops and self-service capabilities to let our students create customized and dedicated virtual workstations. We are also researching on how to best leverage our existing VDI and HPC infrastructure deployments as part of our larger federated and distributed academic cloud project.

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