I can only run 11 server based Virtual machines on my laptop, but all bar three of them are running SQL Server:
The limiting factor I face is RAM - the minimum memory requirements of many of the System Center tools limits what I can cram into to 16Gb, but dynamic memory is a great help here. Anyway it’s a fair increase over the four VM per server density that was discussed when Hyper-V came out. That ratio of virtual to physical can of course be pushed much harder on ‘proper servers’ designed for Hyper-V rather than my laptop mash-up. A good example of this was the labs run at various big events like the Microsoft Management Summit in May where they were able run 225VMs per host although with 128Gbs or RAM they would only be getting a basic 512Mb per machine.
However there is another way and that’s what Microsoft does in its newer data centres, like the one I visited last week. The whole data centre runs on a modified Hyper-V but what’s different is that there are thousands of low cost basic servers rather than hundreds of huge monsters. Blogging in more detail about how these work is more than my job’s worth so if you want to know more then the Global Infrastructure Services site is the place to go (there’s a video tour of one of the data centres here) . However what I can say is that all the lessons learnt from operating at this scale are then put into the next releases of Hyper-V and System Center, for example:
So if you want to get an idea of how to run a data centre at scale then you’ll want to spend your downtime over Christmas learning virtual Machine Manager either by watching the new content on the Microsoft Virtual Academy or by pulling down the Release candidate (which you can install or uses a preconfigured hyper-V virtual machine)