We are in the phase of initiating P2V migration of old hardware servers with possible OS upgrade in order to free some space in DC and reduce energy consumption.
Some of the servers will be merely P2Ved, some requires OS upgrade. I've been thinking on how better to achieve the goal for server which require OS upgrade, but it seems to be not so trivial and applicable to all servers that we have.
Most of the servers are Windows Server 2003 machines and it's planned to upgrade them to Windows Server 2012. Since there is no direct upgrade from 2003 to 2012, it seems more logical to create a new VM with Windows Server 2012 and then transfer application and data to it.
What else are the reasons NOT to perform migration with subsequent OS upgrade so I can have more arguments to convince customers to the approach with creating a new VM and transfering application data?