Upgrading your Domain controllers to Windows 2008 or Windows 2008 R2

So you have been running on Windows 2000 or Windows 2003 AD environment for quite some time and prefer a change. Windows 2008 has been out there for almost 16 months now, including the release of Windows 2008 R2. In this article we’ll discuss some of the key facts you need to consider before you jump into upgrade process and some of the pit falls you need to avoid.

What are the upgrade options available for me?

In-Place upgrade – In this method you can upgrade your existing server to Windows 2008 or Windows 2008 R2. But the key thing is you can't in-place upgrade your windows 2000. You need to upgrade that to Windows 2003. (Do you really need to install windows 2008 on that old hardware :) There are few caveats you need to take into consideration before going this path,

• The Windows Server 2003 patch level should be at least Service Pack 1
• You can't upgrade across architectures (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

Apart from that consider your Domain and Forest functional level as well. In windows 2008 R2 you’ll have some cool roles and features but to get that you need to upgrade the functional levels to R2. Consider the following facts.

Transitioning - Migrating this method means you’ll be adding Windows Server 2008 Domain Controllers to your existing Active Directory environment. After that migrate the FSMO roles to the new server and safely demote the existing windows 2003 domain controllers. You’ll have to purchase new hardware for this. In case if you’re planning to use your existing hardware then temporary you’ll have to bring a new server with windows 2008 to get the roles transferred. Few things to remember at that time is,

• Global Catalog availability
• Enable your new 2008 DCs as DNS servers (if using Microsoft DNS)
• PDC Emulator sync with external time source
• Ensure the demotion of your existing DCs is fully replicated to all your other DCs before promoting the replacement (if re-using the same name and IP address).
• Changes to your backup and recovery procedures
• Anti-virus software compatibility with 2008
  Monitoring software compability with 2008
• Any other services/applications running on your existing DCs (e.g. CA, WINS, DHCP, File and Print).
• Applications and systems that may be impacted during the outage of your DCs during the demotion/promotion (i.e. those that may be hard-coded to the name or IP address).

Transitioning is possible for Active Directory environments which domain functional level is at least Windows 2000 Native. In a way this is my favorite method considering the risky method of in-place upgrade.

Restructuring – In this method you’re going to create a total different domain and transfer the existing domain details (Eg: user accounts, passwords, profiles…etc) to the new domain. One good example is when a company having two or three domains and they wanted to merge to a one domain name. Microsoft ADMT is one of the useful tool in this scenario(Active Directory Migration Tool) Apart from that there are third party tools available to this kind of transition.

when it comes to upgrade your domain environment careful planning is vital in the beginning to avoid unnecessary problems which can be lead to un-reversible. So take good time to read the documentation and do the lab environment tests. Here is a one good article which can give you some useful information.

PM me if you need any assistance on migrating your company domain environment to windows 2008