The devilish details of desktop virtualization
- — 30 September, 2008 09:08
Sweeping infrastructure upgrades
Wilson's infrastructure upgrades included a retooling of his network's points of failure. He used to have two T1 lines at every location, yet twice a year, AT&T would go dark and take out both of them. This wouldn't work in a virtual desktop environment, where "our base assumption is that you will always be connected," Wilson says. "Generally speaking, if you aren't connected, there's very little you can do anyway. Maybe you can write a Word document or work on an Excel spreadsheet, but even then you'll likely need to connect to a file server."
And so Wilson replaced a dedicated T1 line with cable or DSL (depending on the location) and added a Cisco router. Now he says he has three levels of redundancy on different technologies. Also, Wilson added 10 quad-core Dell servers running Citrix XenApp (formerly Presentation Server).
Lifetime installed a powerful MPLS (multiprotocol label switching) mesh network to accommodate the fast transfer of images its engineers needed to work on over thin clients. "Since virtual desktops are mostly used for WAN applications, make sure that your bandwidth and, more importantly, your latency are as low as possible," advises John Bowden, CIO at Lifetime.
Fast storage is another important factor for reducing latency. Fortunately for Natixis, the company had just bought high-end storage from EMC for its SAN. "Reliable, fast storage is key," says Florent Soland, manager of Windows services and virtualization at Natixis. "If you don't have it, it's going to take a lot more time to provision a workstation, and the end-user performance will be very bad."
Infrastructure upgrades throw a monkey wrench into the ROI that desktop virtualization was sold on. Add up the expense of new SAN storage, servers, virtualization software, a connection broker, and thin clients, among other costs, says Soland, "and it's more expensive to roll out 100 workstations in a virtual desktop infrastructure than 100 desktop workstations today -- we're still not there yet."
Au contraire, says Wilson. The reason ROI suffers, he says, is that most companies transition only a part of their workforce to virtual desktops. Indeed, Natixis plans to move 80 percent of its workforce to virtual desktops over the next couple of years. Lifetime's target is only 20 percent. This means they must support two computing models, contends Wilson.
"If you do this piecemeal, then you're only adding another layer and making the stack deeper and more complex," Wilson says. "The key is to deploy this strategically across the board." (To be fair, Natixis cites desktop virtualization concerns, such as licensing and apps that don't work well on virtual desktops, as barriers to a wholesale transition.)