Note: This article has been revised from an earlier version to include Windows Server 2012 R2.
In the list of “Things that keep an Active Directory administrator up at night”, upgrading your Active Directory schema has always been near the top. This concern has been around since Active Directory was first introduced with Windows 2000 and has continued ever since. Why is upgrading your Active Directory schema so concerning? It all boils down to two words: Can’t Undo. An Active Directory schema extension, which is always part of the upgrade to a new release of the Windows Server OS, is extremely difficult to reverse, and only done in the most dire circumstances.
In the intervening years since this process was introduced, however, the ADPREP process has been proven to be very reliable, and excessive worry about this process unjustified. In Windows Server 2012 and R2, Microsoft has gone a step further and streamlined and integrated the ADPREP forest and domain upgrades and DCPROMO domain controller promotion processes into one Active Directory Domain Service Configuration Wizard that takes care of everything.
Let’s step through the process as I upgrade a Windows Server 2008 R2 forest, hosted in Azure IaaS, to Windows Server 2012. My ntservices.net forest has a single Windows Server 2008 R2 domain controller and three sites. I’m going to upgrade using an IT generalist scenario for a small to medium business: I want to add a Windows Server 2012 R2 domain controller in my Active Directory forest to take advantage of many new features (such as new UIs for the Recycle Bin and fine grained password policies), and I don’t want to sweat the small stuff.
To do this, I’ll take a Windows Server 2012 R2 member server and make it a domain controller by following the step-by-step instructions in the Add Roles and Features and AD DS Configuration wizards.
Click on the screenshot below to go to a gallery that show every step of the Windows Server 2012 / R2 domain controller configuration process:
This seamless, integrated process isn’t for everyone; many large environment AD administrators will still want to break up the upgrade process and monitor it closely. For the 80% of Active Directory installations around the world that are cared for by IT generalists, however, this new upgrade and promotion process makes upgrading Active Directory to Windows Server 2012 or R2 a much simpler process.