While desktop virtualization can offer specific advantages over traditional desktop computing around security or
remote access performance, it's a pretty safe bet that the big driver for a lot of people in today's economy is money. Specifically, spending as little of it as possible.
As I wrote a few weeks ago in the article "Virtual desktops -- not less to buy but likely less to maintain," the main way people save money with desktop virtualization is through lower operational expenses. For example, if you have 500 users, it's cheaper to manage them if they're all using desktop virtualization versus if they all have their own fat PCs.
At least that's what the people selling desktop virtualization tell you. But what exactly does "cheaper management" mean? The biggest money saver comes from the fact that desktop virtualization provides an easy way for multiple users (dozens, hundreds or even thousands) to "share" a single disk image. This doesn't mean that you only have to buy one copy of Windows XP that all your users share. It means that the technology allows you to manage one single Windows XP desktop which multiple users can share.
So if you think about all the ways that users can screw things up, what would you rather manage -- one desktop or one hundred desktops? Which is cheaper?
To utilize disk image sharing, you build one single "master" Windows disk image that you want all your users to share. Your desktop virtualization system will then handle the logistics of making on-demand copies of it and providing it to your users. Think of this like the old-days of cloning or "ghosting" a single drive again and again for each user. The only difference is that now it's the desktop virtualization software that does this instead of you. Some examples of this are:
- Citrix XenDesktop uses Citrix Provisioning Server
- VMware View uses View Composer and something called "Linked Clones"
- If you use NetApp for storage, you can use their Flex Clones
Sounds great, right? It is, with one huge caveat. The whole concept of sharing a single disk image across multiple users assumes that all your users are similar enough to share the same image.
But what happens if different users want different apps? That's where this "shared image" concept starts to break down. And as soon as you start making multiple images for different groups of users, the cost savings you got with VDI start to evaporate.
One way to solve this is to create a common "baseline" image that's shared. The idea here is that you install all of your company-wide apps into that baseline image so everyone gets them. And then you can use an application virtualization package to stream each user's personal apps "on demand" into their desktop. So their generic shared desktop becomes their own personal desktop on-the-fly. You can use whatever app virtualization package you want, like Microsoft App-V, Citrix XenApp streaming, VMware ThinApp, InstallFree, etc.
Of course there can be challenges and complexities when trying to virtualize all your applications. But the bottom line is that if you want to get the "big" cost savings of desktop virtualization, you need to start thinking about how you can get all your users to share a common disk image, even if that's just a baseline image.
ABOUT THE AUTHOR:
Brian Madden is known throughout the world as an opinionated, super technical, fiercely independent desktop virtualization expert. He's written several books and over 1,000 articles about desktop and application virtualization. Brian'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. Brian is also the creator of BriForum, the premier independent application delivery technical conference.