I saw a question get posted on twitter that kind of intrigues me a little. The question was pretty straight forward. “How many virtual machines should I be able to run on a host?” That is really a fair question in itself but what I find intriguing is that this is the first question he asks. Is this really the first thing administrators think to ask when designing their environment? After all there is no set formula on how many virtual machines you can run on a host. You can be a little more exact when working with VDI because for the most part all the virtual machines would be set up pretty much the same way and the numbers can be a little more predictable. That would not be the case when working with server virtualization. You are going to have servers all with different configurations and amount of resources provisioned to the virtual machines. This variation is what will change your slot count and the amount of virtual machines you can run on the host.