Note. When Exchange is installed on this particular server you can use this procedure only in a lab environment. To change an Exchange server is not a supported scenario!

When installing an Exchange 2010 environment in my lab I discovered that the Fail Over Clustering bits were not available on my planned DAG members. It turned out that I installed Windows 2008 R2 Standard Edition instead of Enterprise Edition. Even worse, Exchange Server 2010 SP2 was already installed as well.

On TechNet there’s an article that explains how to Upgrade Windows 2008 R2 without using the installation media (i.e. reinstall Windows 2008 R2 from scratch) using DISM, the Deployment Image Servicing and Management Tool.

The supported upgrade paths are:

• Windows Server 2008 R2 Standard -> Windows Server 2008 R2 Enterprise -> Windows Server 2008 R2 Datacenter
• Windows Server 2008 R2 Standard Server Core -> Windows Server 2008 R2 Enterprise Server Core -> Windows Server 2008 R2 Datacenter Server Core
• Windows Server 2008 R2 Foundation -> Windows Server 2008 R2 Standard

To determine the installed version of Windows you can use:

DISM /online /Get-CurrentEdition

To determine possible versions you can upgrade to:

DISM /online /Get-TargetEditions

To upgrade to a higher version of Windows, you can use:

DISM /online /Set-Edition:<Version> /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

The product key is your normal Windows Server product key, but if you’re facing difficulties with your key you can use a temporary setup key from Microsoft as per http://technet.microsoft.com/en-us/library/ff793421.aspx.

So if you want to upgrade a Standard Edition to an Enterprise Edition you can perform this step:

DISM /online /Set-Edition:ServerEnterprise /ProductKey:489J6-VHDMP-X63PK-3K798-CPX3Y

After rebooting the server version now is an Enterprise Edition:

Don’t forget to activate your server with a proper license key of course.

Note. The server that needs to be upgraded cannot be a Domain Controller. In order to upgrade the DC needs to be demoted, upgraded and promoted again.

More information can be found on:

KM Client Setup keys: http://technet.microsoft.com/en-us/library/ff793421.aspx

Upgrading Windows Server 2008 R2 without media http://blogs.technet.com/b/server_core/archive/2009/10/14/upgrading-windows-server-2008-r2-without-media.aspx