When we look at upgrading our existing infrastructure to the latest Windows Server edition we always have to consider the implications when upgrading Active Directory. The first thing you need to plan for is what you are wanting to accomplish in your new migration.
This post provides background information about Active Directory Domain Services in Windows Server 2012 and explains the process for upgrading domain controllers from Windows Server 2008 or Windows Server 2008 R2.
The best place to start is to consider the in place-upgrade scenarios and what can be accomplished in your move.
YES – You can upgrade domain controllers that run 64-bit versions of Windows Server 2008 or Windows Server 2008 R2 to Windows Server 2012. NO - You cannot upgrade domain controllers that run Windows Server 2003 or 32-bit versions of Windows Server 2008.
YES – You can upgrade domain controllers that run 64-bit versions of Windows Server 2008 or Windows Server 2008 R2 to Windows Server 2012.
NO - You cannot upgrade domain controllers that run Windows Server 2003 or 32-bit versions of Windows Server 2008.
To replace them, install domain controllers that run Windows Server 2012 in the domain, and then remove the domain controllers that Windows Server 2003.
See Evaluation Versions and Upgrade Options for Windows Server 2012.
AD DS server role installation changes
In Windows Server 2003 through Windows Server 2008 R2, you ran the x86 or X64 version of the Adprep.exe command-line tool before running the Active Directory Installation Wizard, Dcpromo.exe, and Dcpromo.exe had optional variants to install from media or for unattended installation.
In Windows Server 2012, command-line installations are performed by using the ADDSDeployment Module in Windows PowerShell. GUI-based promotions are performed in Server Manager using a completely new AD DS Configuration Wizard.
To simplify the installation process, ADPREP has been integrated into the AD DS installation and runs automatically as needed. The Windows PowerShell–based AD DS Configuration Wizard automatically targets the schema and infrastructure master roles in the domains where Windows Server 2012 DCs are being added, then remotely runs the required ADPREP commands on the relevant domain controllers.
Prerequisite checks in the AD DS Installation Wizard identify potential errors before the installation begins. Error conditions can be corrected to eliminate concerns from a partially complete upgrade. The wizard also exports a Windows PowerShell script that contains all the options that were specified during the graphical installation.
Taken together, the AD DS installation changes in Windows Server 2012 simplify the DC role installation process and reduce the likelihood of administrative errors, especially when you are deploying multiple domain controllers across global regions and domains.
More detailed information on GUI and Windows PowerShell-based installations, including command line syntax and step-by-step wizard instructions, see Install Active Directory Domain Services. For administrators that want to control the introduction of schema changes in an Active Directory forest independent of the installation of Windows Server 2012 DCs in an existing forest, Adprep.exe commands can still be run at an elevated.
Let’s take a look at Deprecated features and behavior changes related to AD DS in Windows Server 2012
There are some changes related to AD DS:
You can get all the information on issues and other main areas of migrations and upgrades by going to: http://technet.microsoft.com/en-us/library/hh994618.aspx#BKMK_UpgradePaths
if you are new to the product then download the latest bits at: http://aka.ms/msproducts