Scenario: Primary DC 2003 Standard SP1 with two backup DC (2008r2 and 2012r2). We need to move everything to the 2008r2 before the 2003 crashes. I have tried using the “Schmmgmt.dll” instructions with no success: I was able to successfully register the “Schmmgmt.dll”. However, when I used the mmc to move the Schema Master Role nothing happened. I have never done this before so I am not sure what to do next. Any help would be greatly appreciated.
Change your clients to point to the other DNS servers
Transfer the roles to one of the other DC’s (There is no such thing as a backup DC in Active Directory)
Switch off the DC for a period of time, i’d say a couple of weeks.
Once everything is working demote and remove the old DC.