Windows 2008 to windows 2012

Hi,

I have NBU 7.5.0.4 running on windows server 2008 r2. my media servers are also my storage servers.D: drive stores the backup images. I am trying to upgrade these servers into windows 2012. Is there a documentation that explains how to do this kind of transfer without losing my backup data on media servers?

Any thoughts on this would be highly appreciated.