Alas, in many cases, the best option is to set up a test environment and use your direct experiences with it to help plan the scale-out for your expanded user base.[/quote]
I’m a huge fan of XenApp & RDSH having been around since the WinFrame days and never quite escaping. One of the challenges though is that there’s no control over the FrameBuffer used by each session.
One example I’ve seen recently is where an application that works wonderfully with a 1GB vGPU profile in XenDesktop, doesn’t scale linearly in XenApp. The reason for this is that in XenDesktop the application is constrained to the 1GB of graphics RAM, and so manages its utilisation accordingly. When in a XenApp environment, it see’s considerable more (close to 1.6GB) and so consumes more to gain some performance advantage.
The second user comes along and also takes 1.6GB, which is fine, when the 3rd user arrives, they to take 1.6GB, then the 4th user starts a session, they need at least 1GB of framebuffer for a good experience, but the other sessions don’t release their usage, the keep it, and user number 4 get’s just 200MB of Graphics Memory and a poor experience.
To make matters worse, the excess paging of the data that should be in graphics memory to system memory has an impact elsewhere affecting all the other sessions.
Even with a K6000 (12GB of Memory) we could only get 6 sessions running on the host due to the memory challenges, and using K2’s with XenDesktop and vGPU allowed us to hit 16 due to the better memory management.
In this case XenDesktop and vGPU gave much better density than XenApp because of the ability to control the Graphics memory and give consistent performance across the users.
So, you really do need to test, and test under load with the models and applications the users will be working with. As Tobias has stated, he gets very good loads from a server with students that aren’t working on anything complex, but increasing the complexity and the size of the models will lead to an increase in resource requirements.
Colin, I replied to your email to my colleague Mike Wang last night, so you’ve got my direct contact details and we can discuss this in more details if you’d like.