The Big Bang to migration from Windows Server 2003/2008 to Windows Server 2008 R2 is the most straightforward of the migration approaches. The upgrade simply takes all the settings on the domain controllers and upgrades them all to Windows Server 2008 R2. If a Windows Server 2008 installation server handles WINS (Windows Internet Naming) service , Dynamic Host Configuration Protocol (DHCP), and domain name system (DNS) the upgrade process will upgrade all the WINS, DHCP, and DNS  components, as well as the base OS.

This makes a Big Bang migration very attractive, and it can be extremely effective and efficient. However  each of the  prerequisites below must be satisfied:

• The OS on the domain controllers must be Windows Server 2003 SP2 or higher.
• The domain controller hardware exceeds the minimum Windows Server 2008 R2 requirements and all the software is compatible with Windows Server 2008 R2 (this also includes drivers and  antivirus software).
• There is sufficient available  disk space  to perform the OS and Active Directory upgrade. Specifically, the available space must be at least twice the size of the Active Directory database plus the minimum 32GB needed to install the Windows Server OS.
• The current domain functional level is Windows Server 2003 or Windows 2000 Native. Upgrade cannot be done directly from Windows 2000 Mixed, Windows NT 4.0, or Windows Server 2003 interim domain functional levels.

Windows Server 2008 R2 Hardware Requirements

Prior to performing an upgrade it is critical to test the hardware compatibility of any server which will be directly upgraded to Windows Server 2008 R2. The server hardware   should be verified for Windows Server 2008 R2 on the manufacturer’s website or on Microsoft’s HCL (Hardware Compatibility List) at http://www.microsoft.com/whdc/hcl/default.mspx.

Microsoft suggests the minimum hardware levels for Windows Server 2008 R2, but it is  recommended the installation is done on higher spec hardware because the minimum requirements are only for running the base Windows Serve OS and  account of  application loads, domain controller duties, etc. The below is Microsoft’s minimum hardware specs for Windows Server 2008 R2:

• 1.4GHz 64-bit processor
• 512MB of RAM
• 32GB free disk space

Windows Server Version Upgrade

The version of the OS that which will be upgraded is an important consideration in the upgrade process. Windows Server 2003 SP2 or R2, Standard Edition domain controller can be upgraded to Windows Server 2008 R2  Standard Edition or Windows Server 2008 R2 Enterprise Edition.
Continues…