One of the criticisms that’s been leveled at XenDesktop by its competitors is that it is too complex – too many components that have to be configured to get everything to work. And while that’s partially true, it’s not the whole story. As we’ve discussed in previous posts, XenDesktop is extremely flexible in that it allows you to mix and match different kinds of virtual desktops in your environment to best meet the needs of various groups of users. As you bring more kinds of virtual desktops into the mix, you add more infrastructure components to manage them. More infrastructure components = more complexity but also more flexibility.
If you don’t need all that flexibility – if, for example, you just want to deploy “classic” VDI, by which I mean a bunch of virtual PCs running on the hypervisor of your choice – then you don’t need all that complexity, either.
In this video, Dan Feller of Citrix presents a reference architecture for a straightforward VDI deployment of up to 500 users. The video takes about 50 minutes to watch, but it’s worth your time. You’ll learn some interesting things.
For example, you’ll note that Dan is recommending that the XenServers in the XenServer pool that supports the virtual Windows 7 machines should have local disk drives, in a RAID 10 configuration, that will be used for the local host cache for the provisioned Windows 7 systems, for two reasons: First, it’s less expensive than using SAN storage. Second, the limiting factor for how many virtual PCs you will be able to run on a XenServer host is not processing power, and it’s not RAM – it’s IOPS. And he walks you through the calculation of how many functional IOPS the local storage on the XenServer can support, and how many virtual desktops you can therefore reasonably expect to support.
In fact, my only reservation about this video is that, like just about every other discussion I’ve seen regarding Windows 7 virtualization, it doesn’t mention the Microsoft license activation issue that’s inherent in provisioning Vista and Windows 7 desktops, the need for the Microsoft Key Management Service, and the nuances of getting KMS to work properly. But we’ve pummeled that issue elsewhere in this blog.
So, with that in mind, heeeerrrrrreeee’s Dan (P.S.: the audio doesn’t start until about 15 seconds into the video):