Upgrading a Windows NT 4.0 domain to Windows Server 2003 and Active Directory (AD) is a special challenge for small networks. It's not always as easy as putting in the Windows 2003 CD-ROM and clicking the Upgrade now button. The challenges include the following:
- Small networks might have only one NT 4.0 domain controller (DC), so there is no BDC for recovery purposes if the upgrade goes awry.
- The existing DC probably doesn't meet the hardware requirements for Windows 2003, or there isn't sufficient space on the system partition to upgrade the server.
- The new server can't be loaded with NT 4.0 as a BDC because of driver problems.
- The present domain structure must be kept, but the domain structure needs to be on a Windows 2003 DC.
At my company, we've developed a step-by-step process to upgrade older NT 4.0 domains to Windows 2003 and AD. This process follows the standard upgrade procedure of taking a BDC offline during-the upgrade and leaves the customer with a new Windows 2003 DC running AD on new hardware.
For example, let's say you need to upgrade a corporate domain named company.com. Four machines will take part in the domain upgrade:
- ServerNT4 (the existing NT 4.0 DC)
- Server2003 (the new Windows 2003 DC with AD)
- TempServerA (an old Compaq Proliant 800 server to be used as the domain upgrade server)
- TempServerB (an old CompaqAP200 workstation to be used as the offline BDC)
Selecting suitable temporary machines is important because NT 4.0 doesn't install on many new machines. Likewise, Windows 2003 doesn't upgrade on many older machines. TempServerA must be supported by both NT 4.0 and Windows 2003. TempServerB can be any older workstation for which NT 4.0 has default network drivers.
Here are the upgrade steps:
- Place TempServerB in the company.com network and install NT 4.0 on it. Choose to make it a BDC in the company.com NT 4.0 domain. Shut it down, and set it aside. If all goes well, this machine won't be needed again.
- Place TempServerA in the company.com network, and install NT 4.0 on it. Choose to make it a BDC in the existing company.com NT 4.0 domain. Install SP6a, then promote TempServerA to a PDC. When the servers are fully synchronized, run the Windows 2003 upgrade on TempServerA. TempServerA is now the Windows 2003 AD DC.
- Place the new server, Server2003, in the company.com network. Install Windows 2003 on it if you haven't already done so. Run dcpromo on Server2003, which will make Server2003 a DC in the company.com domain.
- Transfer the Flexible Single-Master Operation (FSMO) roles from TempServerA to Server2003. Your new Windows 2003 AD DC is ready to fly. Run a backup.
- Demote TempServerA with dcpromo, and remove it from the network. Its work is done.
- ServerNT4 can remain in the company.com network as long as it's needed or until any programs and data are moved to Server2003. Then, ServerNT4 can be shut down permanently.