We use Oracle RAC (2 node) 18.104.22.168 on Windows 2008r2 and we must uprgade Windows to 2012. On test mashine (node1) we upgrade Windows but CRS don't starting on OS with Windows 2012.
On old node with Windows 2008 RAC is workit.
As a result, it's bug on stack Windows 2008 + Windows 2012 + Oracle 11.2.X.X the error lies in the service Oracle in Windows 2008 running with user nt autority\system (lower letters) but in Windows 2012 user NT AUTORITY\SYSTEM in (capital letters).
In OLR file uses user nt autority\system (lower letters) but in Windows 2012 this user in capital letters and in end we have error and GRID no started.
On support.oracle.com we found many notes about similar bugs and the to fix we must deconfig oracle grid and etc.
I need help in best practis on upgrade Windows with use Oracle RAC.
I'm think thet beefore upgrade the OS we must delete Oracle Instance and Oracle Grid. On next step Upgrade OS and install GRID and Instance on upgrade node. But i dont know can Oracle RAC work on different OS Windows 2008\2012 ?