For years, I've been shouting that desktop virtualization is more difficult than server virtualization, but I recently realized that I have never actually explained why. Sure, I've written about why desktop virtualization is different from server
There's a danger in this, of course. Much like every parent thinks his or her kid is cuter and smarter than everyone else's, most IT pros think that their own slice of the IT industry is actually more difficult than any other. So to that end, let's look at why desktop virtualization is much more challenging than server virtualization.
By far the biggest challenge with desktop virtualization is the users. (OK, that's the biggest challenge with any segment of IT.) At the end of the day, IT's job is to provide applications and data to users in a secure and cost-effective way. That's accomplished by standardizing things. Making everything the same makes it easy to spot anomalies that signal security problems. Standardization also simplifies management and support, and it squeezes out costs.
So if you're talking about a bunch of physical servers in a data center, virtualizing them is essentially a form-factor change. From the outside, a "server" isn't anything really -- it's just what's on the other end of the network cable that responds to a certain IP address. Users don't care whether a server is physical or virtual any more than they care whether it's a blade or rack or whether it's a Dell or HP.
But when it comes to desktops, the attitude toward hardware design is very different. Users have very strong opinions about their desktops and laptops. After all, users can freak out over something as trivial as the location of the power jack on a new laptop -- and that's doesn't even really matter. Imagine if we want to virtualize their desktops, and we tell them that they can't use their favorite apps or that they have to use a certain device or that they can't work offline. There'd be a revolt!
Another particular desktop virtualization challenge is that it's really hard to go just "partway." With server virtualization, it's easy to identify the straightforward candidates for migration and to virtualize only those servers while leaving the tricky stuff on physical ones. But we can't just virtualize half of a user's desktop. (Well, we could, but then we'd have to provide users with two desktops -- their old physical ones and their new virtual ones -- and that would actually create more work for us. In that case, we should just stick to the traditional desktop or virtualize just a few applications here and there with app virtualization or a terminal server.)
The final challenge unique to desktop virtualization is that users interact far more with their desktops than with servers. And this means that we have a higher bar to meet in order to keep users happy. No user would notice if a server suddenly started to respond a few milliseconds slower, but if an interactive desktop slowed down, the help desk would light up like a Christmas tree.
So with all that, plus that fact that desktops running on hypervisors need to be treated like servers -- in terms of service-level agreements, change control, etc. -- we see that desktop virtualization truly does have its own challenges that our server-based peers don't have to deal with.
ABOUT THE AUTHOR
Brian Madden is an independent industry analyst and blogger, known throughout the world as an opinionated, supertechnical desktop virtualization expert. He has written several books and more than 1,000 articles about desktop and application virtualization. Madden's blog, BrianMadden.com, receives millions of visitors per year and is a leading source for conversation, debate and discourse about the application and desktop virtualization industry. He is also the creator of BriForum, the premier independent application delivery technical conference.