You might be running Windows Server 2003 and Windows Server 2003 R2 Domain Controllers at the moment and you're looking to replace these servers with Windows Server 2008 Domain Controllers to utilize the new features of Windows Server 2008. You might also be looking to replace your aging Windows Server 2003 and Windows Server 2003 R2 Domain Controllers with spanking new Windows Server 2008 Domain Controllers, while keeping your Active Directory running smoothly.
Ways to migrate
Upgrading your Windows Server 2003 Active Directory environment to Windows Server 2008 can be done in three distinct ways:
- In-place upgrading: Windows Server 2003 and Windows Server 2003 R2 can both be upgraded in-place to Windows Server 2008, as long as you keep the following in mind:
- The Windows Server 2003 patchlevel should be at least Service Pack 1
- You can't upgrade across archtectures (x86, x64 & Itanium)
- Standard Edition can be upgraded to both Standard and Enterprise Edition
- Enterprise Edition van be upgraded to Enterprise Edition only
- Datacenter Edition van be upgraded to Datacenter Edition only
In-place upgrading requires you to run adprep.exe before starting the upgrade process on the Domain Controllers. Check this post from Jorge for more information.
- Transitioning: Migrating this way means adding Windows Server 2008 Domain Controllers to your existing Active Directory environment. After successfully moving the Flexible Single Master Operations (FSMO) roles you can simply demote the previous Domain Controllers, remove them from the domain and throw them out of the window.
Transitioning is possible for Active Directory environments which domain functional level is at least Windows 2000 Native.
- Restructuring: A third way to go from Windows Server 2003 Domain Controllers to Windows Server 2008 Domain Controllers is restructuring your Active Directory environment. This involves moving all your resources from one (Windows Server 2003) domain to a new and fresh (Windows Server 2008) domain. Using tools like the Active Directory Migration Tool (ADMT) are priceless in these kind of migrations.
Reasons to transition
I feel transitioning is the middle road between the two other ways to migrate to Windows Server 2008:
- Restructuring means filling a new Active Directory from scratch
- In-place upgrading means you're stuck with the same hardware and limited to certain upgrade paths
- Transitioning means you get to keep your current Active Directory lay-out, contents, group policies and schema. Transitioning also means moving to new machines, which can be dimensioned to last another three to five years without trouble.