In “VDI licensing: Beware the under-$40-per-desktop promise” on SearchVirtualStorage.com, the author makes a good point about how unrealistic VDI licensing cost claims may be. The
The key driver for most projects seems to be return on investment. With server virtualization, companies replaced physical servers with virtual ones, typically saving money in one or more areas, such as hardware costs, power consumption, data center space, storage costs or management overhead. Obviously, mileage would vary, but generally the ROI was pretty straightforward. Cost-justifying a VDI storage project, however, probably won’t be so easy.
VDI perceptions vs. reality
Why is the ROI for VDI so different from that of server virtualization? Well, for starters, VDI isn’t replacing a potentially expensive server that’s being used at single-digit percentages. It’s trading a much cheaper desktop computer for a portion of a much larger data center asset. It’s also trading relatively low-cost office work space for much higher-cost data center rack space. And storage can actually cost more in a VDI implementation since enterprise storage systems can’t typically compete on a price-per-gigabyte basis with the consumer-grade disk drives that are put into desktop computers. While there’s more to storage TCO than just disk drive acquisition costs, it is the most visible component.
To some extent, this is a situation similar to what the first SAN vendors ran into, where direct-attached storage was so cheap and easy to deploy that users often had a tough time seeing the cost savings of consolidation. Over time, with enough scale and the maturity of technologies such as Fibre Channel, consolidation usually won out, especially after administrators got familiar with the new infrastructure and the management tools that were available. But at first blush, consolidation can seem like a bad idea, at least from a pure cost perspective.
In addition to unmet expectations around storage costs for each newly virtualized desktop, users could also experience performance problems. Due to VDI storage’s unique IOPS requirements, the storage they’re using may not be up to the task of supporting hundreds or even thousands of virtual desktops. VDI environments have to handle intense I/O activity, or “I/O storms,” such as during morning boot-up and end-of-day data saves. And there are other common events, such as software patching or anti-virus updating, that can create the concentrated storage activity that results in slow applications and unhappy users.
Managing VDI expectations and solving performance problems
For VARs, the solution is to set expectations up front and help customers realize they won’t get the kinds of ROI results they may have seen with a server virtualization project. In the long run, the real economics revolve around opex and saving on overhead by making investments on equipment. Unfortunately, people are usually impatient, and a longer-term payback must be explained early and often over the course of a VDI project. So you have to get out in front of a potential problem and not wait for the customer to call after he’s run his own ROI numbers -- which may very well be inaccurate.
The opportunity can come in accounts where you didn’t sell the VDI project or the storage supporting it. These customers may have some pain with storage performance or reliability because they were sold storage that doesn’t really handle the special challenges VDI storage can pose. You can leverage your line card to put together some solutions -- possibly incorporating solid-state storage in a tiered or caching architecture -- and accommodate these I/O storms better than a standard storage array can. Or, you can provide this high performance add-on to an existing storage system and get a positive result.
VDI environments also include a lot redundant data since the image files created for each virtual desktop are usually very much the same. Storage systems that include features such as deduplication, thin provisioning, and writable snapshots or clones can save storage space and reduce the administration time required to manage the virtual desktop environment. Similar to the performance challenge, the capacity challenge can offer an opportunity for you to educate potential customers on ways to make VDI storage more efficient and demonstrate your value-add.
Eric Slack is a senior analyst with Storage Switzerland.
This was first published in November 2011