There are two general strategies you can pursue when moving from an Active Directory Forest that has domain controllers running Windows Server 2003 to an Active Directory Forest with domain controllers running Windows Server 2012 R2.
- Perform a forest upgrade
- Perform a forest migration
Forest migration is easily the trickier of the two. This is because with a forest migration, you’ll need to create some or all of the objects that are present in the source forest in the destination forest. The benefit of an Active Directory migration is that you can (theoretically) get rid of much of the cruft that may have built up in your Active Directory environment over time. The drawback is that if you have active directory integrated applications, like Exchange, this process is going to be complicated.
Upgrades are far more straightforward, but you won’t be required to perform the sort of spring cleaning operation that you would with a migration, simply because you can just upgrade Active Directory without worrying whether or not all the objects that you are upgrading are still necessary. When you perform a migration, at some point you’ve got to decide whether an object should or should not be migrated, and that decision takes time.
At a high level, upgrading Active Directory from Windows Server 2003 to Windows Server 2012 R2 is fairly straightforward:
- You add Windows Server 2012 R2 member servers
- You promote them to domain controllers
- You transfer FSMO roles across from the Windows Server 2003 domain controllers to the Windows Server 2012 R2 domain controllers
- You demote the Windows Server 2003 domain controllers
In the next few blog posts, we’ll talk more about the complexities and challenges of migrating Active Directory from Windows Server 2003 to Windows Server 2012 R2.