Many believe that virtual desktops are the gateway to easier desktop deployment. They are until a certain period of time passes when you realize you still must maintain your desktops. The goal of many virtual desktop implementations is to reduce the number of desktop images that must be maintained. Recently, I’ve had quite a few discussions with organizations around operational type items in their desktop virtualization environment, and here is what I’ve come to realize… not many people are focused on operations.
Honestly, who wants to maintain the desktop? It is sooooo boring. It’s so much cooler to build and move on. But someone has to maintain the desktop virtualization environment. Someone has to maintain it in a way that doesn’t screw up the infrastructure. You don’t think a poor desktop management can cause issues in virtual desktop infrastructure, then let me tell you a story…
The XenDesktop environment as designed to use Provisioning services to stream three images to 1,000 desktops. It was determined that the Provisioning services server would require roughly 8 GBs of RAM to support the Windows Server OS as well as caching a portion of each desktop image into the system cache (We don’t want to over allocate RAM as it costs money). After some time, the desktop team starts creating new desktop images because they are fairly easy to do. The image count slowly approaches 10 images.
What now happens does not kill the environment; it just makes the design less than optimal. With 10 images, we won’t have enough system cache on the Provisioning services server to store the most common portions of the virtual image. This means Provisioning services must read the virtual image blocks more often, which puts added pressure on the storage. Because disk is slower than RAM, this also can induce latency within the stream, impacting the user experience. This happens slowly as more desktop images are allocated. It’s very similar to how your physical desktop gradually slows down as you add more and more applications and utilities. You don’t really notice it at first, but after a while you start to think “Hey! Didn’t this thing use to run a lot faster?”
And if we go beyond the user aspect and focus on the desktop admins, they will now have to update many more images, which must be distributed into the environment.
What does this all mean? It means that virtualizing the desktop is more than focusing on the technology. You have to focus on the operational aspects as well. If you don’t, you will end up with a virtual mess.
Daniel – Lead Architect