Understanding installation options
Installation options were first included in Windows Server 2008, which included the Windows Server Core installation option in addition to the traditional or Full installation option. While the Full installation option included everything you expected in a Windows installation, Server Core included only those services and features needed to support common infrastructure roles such as domain controllers, DNS servers, DHCP servers and other common roles to reduce footprint, attack service, and servicing overhead. Most of the GUI was also removed from Server Core, which meant no desktop, no taskbar or Start menu, no MMC consoles, and so on. The primary UI in Server Core installations is the Windows command prompt, which meant you needed to use the command-line (or better, scripts) to configure Server Core machines.
In Windows Server 2008 and Windows Server 2008 R2, you had to select which installation option you wanted (Server Core or Full) when you installed your server. If you installed a server as a Server Core installation, you couldn't change it to Full without reinstalling and vice versa. This now changes in Windows Server 2012, which allows you to convert a Server Core installation to a Server with a GUI (the new name for Full) installation or vice versa.
Benefits of converting installation options
Being able to convert between GUI and Server Core installations after deployment has significant benefits. For example, let's say you want to deploy Server Core in a virtualized environment like a private cloud because its reduced footprint will enable higher levels of workload consolidation on your virtualization hosts. But you're a bit scared of having to use commands and scripts to configure your Server Core virtual machines after you deploy them to your private cloud.
With the ability in Windows Server 2012 to convert between installation options after deployment, you can sidestep this issue by simply deploying your VMs with the GUI installation option instead. Then post-deployment you can configure your new servers using familiar GUI tools like MMC snap-ins. Once your servers have been configured properly, you can then convert them to Server Core installations so you can pack more VMs onto your Hyper-V hosts to save money.
Converting from Server with a GUI to Server Core
Click the icon on the taskbar to open the Windows PowerShell console and run the following PowerShell command to remove the GUI management tools and desktop shell from the server and convert it into a Server Core installation:
Uninstall-WindowsFeature Server-Gui-Mgmt-Infra -restart
The PowerShell console first collects data concerning the server's configuration and then begins removal of the GUI management tools and desktop shell:
Once these components have been successfully removed, the server restarts and you're presented with the logon screen:
Pressing CTRL+ALT+DEL lets you enter your credentials for the server:
Note in the screenshot above that there is no avatar image for the user, which indicates right away that you're logging on to a Server Core installation. Once your credentials have been authenticated, the stripped-down Server Core UI is displayed as expected:
Converting from Server Core to Server with a GUI
Now let's convert our new Server Core installation back into a Server with a GUI. Begin by typing powershell into the Server Core command prompt to launch the Windows PowerShell console:
Run the following PowerShell command to add back the GUI management tools and desktop shell to the server and convert it back into a Server with a GUI:
Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell –Restart
Once again, the PowerShell command starts by collecting data concerning the server, then it begins installing the components needed to convert the server back into a Server with a GUI:
The server then restarts and you're presented once again with the logon screen:
This time when you press CTRL+ALT+DEL you'll see an avatar icon when you enter your credentials:
Once you've logged on to your server, you can verify that it's once again a Server with a GUI:
Additional details
The above steps only work if you initially deployed your server using the Server with a GUI option. If you initially installed it as a Server Core machine, you'll need to go through a few extra steps to convert it into a Server with a GUI. These steps are outlined in the section titled "To use Windows PowerShell to convert from a Server Core installation to a Server with a GUI installation" on this page of the TechNet Library.
While Windows Server 2012 only includes two installation options, there is a third option called Minimal Server Interface that you can configure post-deployment. The Minimal Server Interface is similar to Server with a GUI but is missing certain UI features:
- The desktop and Start screen
- Windows Explorer
- Internet Explorer
However, the Minimal Server Interface does still include the following UI features to allow you to easily manage your server:
- The new Server Manager
- MMC consoles and snap-ins
- Some Control Panel applets
To configure a server to use the Minimal Server Interface option, you can use the same Install-WindowsFeature and Uninstall-WindowsFeature shown above but specifying only the Server-Gui-Mgmt-Infra parameter.
If you already have a Server with a GUI installation, then besides using the PowerShell commands shown above you can also use the new Server Manager to remove the GUI management tools and/or desktop shell to convert your server to either a Server Core installation or a Minimal Server Interface server. To do this, launch the Remove Roles wizard from Server Manager and clear one or both of the checkboxes shown under the User Interfaces and Infrastructure feature.
Since both the new Server Manager and PowerShell 3.0 can be used to manage servers remotely, these tasks can also be performed on remote servers in your datacenter from your admin workstation.
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