I have 50+ Windows Servers with 2008 R2 OS, they have diverse roles installed, like some are DCs with DNS, DHCP, etc. Some are File Servers, Print Servers, WTS Servers, IIS and so on. They are all VmWare VMs. We are planning to upgrade them to 2012 R2. The question is about the best and not-so-painful way to do this. Some guys suggested me to create secondary VMs and install 2012 R2 on it, migrate the roles and then turn off the old ones. I have even tested in lab the media (in-place) upgrade with DC roles and all the stuff installed and working. It upgraded surprisingly quite easily and fast, and everything came back normally. But I don't know if this is the best practice. Do you guys have any suggestion?
Thanks in advice.