Windows Server 2012 & Features on Demand

If you’re anything like me, typing at a keyboard all day is about all the exercise you get.  I’ll admit it, over the last couple months I’ve packed on a couple pounds.  I just told myself, woman love the stellar I.T. body look.  A gut almost touching the edge of the desk, the hump in the back from bending over the keyboard all day.  The none stop drinking of caffeinated soda.  So how’s a guy like me suppose to drop some weight?  Exercise!  Ha, yeah that’s not going to happen, but I wonder how much liposuction costs?

It’s easy for humans, hook up a hose, and suck out all the fat.  But what about your servers?  Gigs, and gigs of data are taking up hard drive space, and as time goes by, the plumper your server will become.  Soon you’ll be left with barely any free space.  Now what if I told you there is something you can do?  A sort of liposuction for your server.  Thanks to Windows Server 2012 Features on Demand , it’s now possible.

With Windows Server, we have what’s called the WinSxS (Windows Side By Side) folder.   This folder is located in the Windows directory.  (C:\Windows\WinSxS)  The folder contains all the files that are required for a Windows installation of a feature or role.  The advantage of this folder is you can install a role, or enable a feature without the source media.  The disadvantage of this folder is, it makes your server fat!  I’m talking Gigabytes of data just sitting there waiting for the day you install a new role.  But what if that day never comes?  All that good hard drive space going to waste.  Luckily with Windows Server 2012 you can now reclaim that space with PowerShell.

Features on Demand

In Windows Server 2012, you can minimize the footprint of your installation by uninstalling the files from your WinSxS folder.  This ability is called Features on Demand.  The only catch is, if you ever would want to install a feature you removed, then you would need to access the Windows Server 2012 source files.  Okay, lets put our server on a diet.

It’s a fairly simple process to uninstall these roles or features files from disk.

1. Open Windows PowerShell as Administrator.

2. Type the following: Uninstall-WindowsFeature –Name <feature_name> –Remove

3. That’s it!

Okay so for example I would run the following command to remove DHCP WinSxS files.

 Uninstall-WindowsFeature –Name DHCP –Remove 


Run the following, if you would like to remove all the role and feature files that currently are not installed on the local server.

 Get-WindowsFeature | Where-Object -FilterScript { $_.Installed -Eq $FALSE } | Uninstall-WindowsFeature –Remove 


Don’t worry, you can reinstall these feature files at any point.  To do so, run the following PowerShell command.

 Install-WindowsFeature <featurename> -Source wim:<path>:<index> 

How do you know what index number to use?  Simple.

 Get-windowsimage –imagepath <path to wim>\sources\install.wim 


I’m running Windows Server 2012 Datacenter, so I selected “index 4”.  Now if I wanted to reinstall DHCP onto this server I would type the following command:

 Install-WindowsFeature DHCP -Source wim:d:\sources\install.wim:4 


You can alternatively reinstall a feature by using Server Manager. Run the Add Roles and Features Wizard, select what you want to install, and then at the Confirmation screen “specify an alternate source path”.


The –Source option can access the files in there different ways.

  1. Searching the location you specified during either your PowerShell command or during the Wizard.
  2. Group Policy Settings: Computer Configuration\Administrative Templates\System\Specify settings for optional component installation and component repair.
  3. Searching Windows Update

Create a Feature File Store

Before we end, I would also recommend setting up a feature file store.  Instead of searching for the media disk, just copy the Sources\SxS folder from your Windows Server 2012 installation media to a network share.  For example, \\network\share\sxs.  Then when you want to reinstall a feature, just point the –Source to your new network share.

Hopefully you now have a leaner server.  Man, all this weight lost talk has gotten me hungry.  I think its time for a Baconator!