To say that virtual desktop infrastructure (VDI) is making a comeback would be a bit of an overstatement. Of course, the technology has come a long way since the 1960s, when pretty much everyone using a computer worked in virtual sessions akin to terminal services such as Citrix Systems' XenApp and Microsoft Windows Server Remote Desktop Session Host (RDSH).
Today, there are three main flavors of VDI, desktop virtualization or remote desktop: Terminal services, persistent desktops from VMware and Citrix - who collectively own 90 percent of the market - and non-persistent desktops that include a stored user profile. (The term "VDI" refers to all three flavors and their associated infrastructure.)
Persistent desktops represent an image of the user's PC stored in the data center. This is the Cadillac of VDI rollouts, meaning it's the most expensive and infrastructure-intensive, but it's also the most desirable from a user point of view.
Non-persistent desktop images and terminal services, meanwhile, are temporary desktop sessions that, once terminated, return to a shared pool for someone else to use. The big difference between the two is that terminal services are aimed at workers such as call center representatives who don't need personalized desktop images or applications.
Non-persistent sessions, on the other hand, can be stored with an associated user profile. When a user logs back in, he starts up where he left off and can customize his settings and applications. It's like a persistent image, only without the associated storage- and server-side overhead. Even though it's not the same as a true one-to-one experience, it comes with some of its own storage overhead, as changes must be saved over time, this makes the most sense for some adopters in terms of cost and user experience.
VDI Deployment Easier Now That Tech's Cheaper, Faster
Until recently, anything but terminal services was considered too infrastructure-intensive for everyday office and knowledge workers. But new technologies and falling prices have made VDI a viable and cost-effective alternative to putting workstations on every desktop, says Kevin Strohmeyer, director of product marketing for desktops and applications at Citrix.
"What we've seen over the last 12 to 18 months is massive in-line deduplication technologies, host-based cache technology - basically, the realization that, with so many desktop [virtual machines], you've got the same images running copy after copy after copy on the server," Strohmeyer says. "Why do I have to send all my reads and writes out to central storage to operate these big farms of VMs? Why can't I stash and operate those locally?"
As for pricing, Strohmeyer says Citrix partner NetApp offers "all-in" VDI storage setups for $35 per user. A few years ago, that number would have been as much as $500.
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