The case for virtualized desktop infrastructure (VDI) technology looks pretty simple on paper. By using dumb terminals, CIOs can reduce costs for both hardware and hard-asset maintenance and save administrative effort. In many cases, one desktop image can be used for the many employees who don't have custom requirements. As machines are eliminated one by one, patching, software installation and so on are reduced. The choices for VDI, however, aren't that simple: CIOs have to decide whether to go with thin clients or go for the full load reduction with zero clients.
Thin client devices have some local compute capacity and offload more intensive requirements to the network. These devices still have a CPU, local random-access memory and storage. Thus, even if they're smaller than typical corporate-issue PCs, they still involve a cost footprint. Zero clients, meanwhile, reduce the load to almost nothing. A true zero client has no operating system, CPU or memory located at the employee's seat. It's basically just a port replicator for some Universal Serial Bus devices and a dumb terminal. Zero clients represent essentially a one-time investment with next-to-zero maintenance costs.
The benefits of zero clients look sexy. You reduce complexity, centralize management, save money and probably provide better service to your users -- at least from the perspective of corporate performance. But they're no nirvana. Any company that markets their zero client wares as a no-lose proposition is simply lying. Before you jump onto the playground with VDI, here are some pitfalls to look out for when considering zero-client and thin-client technology:
Does a thin client approach really save you money? Make sure that if you want to go zero clients, you actually get zero clients.
- Make sure zero-client-based products truly use zero-client hardware. Thin clients don't solve the same types of problems that zero clients do. Thin clients have operating systems that have to be managed, either as Windows domain members or with a third-party suite of management tools that touch each device. And those operating systems have to be patched. The storage in a thin-client device can go bad -- with bad heads, bad platters or other problems. And corporate "fleet" PCs have gotten very inexpensive, to the point where you're looking at $300 to $400 for a reasonably good device right out of the gate. Does a thin-client approach really save you money? Make sure that if you want to go zero clients, you actually get zero clients. Purchased in bulk, these devices should be $100 or lower per seat.
- Some zero clients require proprietary hardware at the server and on the client side. Watch for this type of integration. The true motivation here is seamless integration with your existing data center assets, along with a really low-cost device deployment. Having to purchase extenders, management suites and data packs to bring rich media and graphics support to your users can really defeat any sort of cost savings you hope to achieve from zero clients or thin clients. (See Dell Inc.'s Wyse products for a great example of an environment much more complex than it needs to be, in my opinion). The licensing fees will be expensive in these types of deployments, and making all the software suite's pieces fit together will be an administrative headache as well. Simpler is better here. Most recent versions of Windows have sophisticated tools built in to support a wide range of VDI and session-hosting scenarios. A lot of third-party software "muscle" simply is not required to make things work. It's the same with hardware: Products that require a 1:1 mapping of hardware at the employee seat and in the data center (like those from Teradici Corp.) don't save much money at all. You're just putting the compute capacity into a different place.
- Consider bandwidth concerns. Apart from the obvious graphics-intensive roles (like computer-aided design, computer-aided manufacturing and video production) that would make zero client devices unsuitable in all cases, consider whether you've invested in other heavy-bandwidth applications. Such PC-based communications and Voice over Internet Protocol products as Microsoft Lync or Cisco Communicator have huge bandwidth considerations if you're adding a significant workload to your existing network assets in the form of session hosting. What was once good enough for just data use and voice traffic might not be good enough when all of your users' activity has to go through the network because they are using zero-client devices.
More about the VDI model
- If you're a Microsoft shop that uses Hyper-V, be careful. Many vendors work closely with VMware Inc. to broker connections, balance the load and enable other VDI solutions, such as pooled and assigned virtual machines. These providers' wares might not work -- or might not work as extensively -- if you use Microsoft's Hyper-V as your hypervisor. Be sure to schedule tests and procure evaluation units so you're fully aware of the limits of the product you choose when it comes to which data-center back end works.
What do you think about VDI? Are you deploying it in your organization? Have you had much success with thin clients or zero clients? Discuss in our new comments section below.
Jonathan Hassell is president of 82 Ventures Inc., and an author, consultant and speaker in Charlotte, N.C. His books include RADIUS, Learning Windows Server 2003, Hardening Windows,and most recently, Windows Vista: Beyond the Manual. Write to him at firstname.lastname@example.org.