I'm not sure if this question is best asked on the SQL forums, or the Hyper-V forums. So I'll just start here.
I have 2 physical Hyper-V hosts that are hosting all of our SQL VMs. They are new machines, fast, with lots of RAM, but only have dual 6-core CPUs (per core licensing is expensive!). Each VM is part of a 2-node SQL AlwaysOn cluster, one node per host. I want move my Skype for Business databases into an AlwaysOn Availability Group, but I'm not sure what's a better option. Either I can create two new SQL VMs, and put the databases on dedicated Windows VMs, or move the databases into one of the existing AlwaysOn clusters that are already running on that hardware. I'm worried that adding too many VMs on a relatively small number of CPU cores will eventually cause contention amongst all VMs running on that hardware. But I don't know where that line is.
So I guess the question is... is it better to have fewer, but larger VMs hosting a whole ton of databases, or many smaller VMs hosting dedicated applications (like Skype)? How do I find real information in my environment to help me make this decision?