Windows 2008 Active Directory

Over the last few years, Windows 2008 has replaced the ageing Windows Server 2003 and Windows Server 2003 R2 domain controllers. However, performing any task where one has to upgrade from the earlier versions of the Windows Server DC to Windows Server 2008 without causing any disturbance in Active Directory is definitely a big task and challenge as well. The shift requires selecting the best possible method of migration and other important steps involved in the process.

Let us first look at the options available for migration from Windows 2003/ 2003 R2 Active Directory service to Windows 2008 Active Directory.

In-place Upgrading: Both Windows server 2003 and 2003 R2 can be upgraded in-place to Windows 2008 Server. For in-place upgrading, administrators are required to run adrep.exe before initiating the up gradation process in the domain controllers. Adrep.exe is executed to prepare the Active Directory environment before introducing Windows Server 2008 domain controller. This Microsoft utility is run with the following commands in Windows 2008 Active Directory:

'ADPREP /FORESTPREP' (For Schema Master)

1. Executed on domain controller Schema Master FSMO
2. Updates the AD forest
3. Does not change the "Partial Attribute Set"

'ADPREP /DOMAINPREP' (For Infrastructure Master)

1. Executed on Infrastructure Master FSMO
2. Updates the AD domain

ADPREP /DOMAINPREP /GPPREP' (For Infrastructure Master)

1. Executed on the Infrastructure Master FSMO
2. Updates AD domain and the SYSVOL

ADPREP /RODCPREP (For Read only domain controllers- optional)

1. Executed on the Domain Naming Master FSMO
2. Updates permissions on application partitions for an RODC to be able to participate in their replication
3. Only executed when upgrading from W2K3 AD

Restructuring: In this method, administrators are required to restructure the entire Active Directory structure. For this all the resources have to be moved from one domain to another. Active Directory Migration Tool (ADMT) is the best utility that is used for restructuring the Windows 2008 Active Directory environment.

Transitioning: With transitioning, it is possible to add the Windows 2008 domain controllers to the existing Active Directory environment. In this migration process, the first step must be to move the FSMO (Flexible Single Master Operations) roles. Next, the previous domain controller must be demoted to remove it from the new domain on Windows Server 2008.

Of all the three methods, transitioning to Windows Active Directory 2008 is best since restructuring means creating the entire directory from the scratch and with in-place upgrading administrators are stuck with limited upgrade paths. Whereas transition procedure allows administrators to retain the existing Active Directory layouts, schema, objects, contents and group policies.