How to shrink C drive in Windows Server 2012 (R2)?

If you do not know or forget to edit disk when installing Windows Server 2012, entire disk space will be used for System Reserved and C drive. As we know, it is NOT good idea to use large and single system C drive, putting everything into it. The best idea is dividing the disk to several partitions, one for system partition, one for applications, the others for data and backup. Luckily, you can shrink C drive to release free space and then create new drives after installation. In this article, I’ll show you how to shrink C drive (system partition) in Windows Server 2012.

There are two ways to decease C drive space – Windows built-in Disk Management and 3rd party software. The benefit of Server 2012 Disk Management to shrink system partition is No down time, but in the meantime, you cannot shrink C drive with large amount of space in some conditions. In this case, 3rd party software will help you.

Shrink C drive in Disk Management

Step 1: Open Windows Server 2012 Disk Management (right-click Windows on bottom left in Desktop, and then select Disk Management).

Step 2: Right click the C drive and select “Shrink Volume“.

Step 3: Enter the amount of space to shrink in MB, click Shrink to proceed.

In some cases, you cannot shrink or can only shrink little space, as the note says “You cannot shrink a volume beyond the point where unmovable files are located.”

Why cannot shrink the system partition

From Microsoft explanation, when you shrink a partition, certain files (for example, the paging file or the shadow copy storage area) cannot be automatically relocated and you cannot decrease the allocated space beyond the point where the unmovable files are located. If the shrink operation fails, check the Application Log for Event 259, which will identify the unmovable file.

With 3rd-party software such as NIUBI Partition Editor, there is no such limitation, because it is able to move the “unmovable” files.

Shrink C drive with partition software

Comparing with Disk Management, 3rd-party software has more options to shrink partition. Besides shrinking volume, you can move the Unallocated space to other position and add it into other drives.

Simply decrease C drive space

Better than Disk Management, with partition software you can decrease C drive space and create Unallocated space at the right OR left side. It is also able to shrink C drive to minimum size even if there is unmovable file.

Step1: Download NIUBI Partition Editor, right click C drive and select “Resize/Move Volume“.

Shrink c drive

Step2: In the pop-up window, drag the left or right border to shrink it.

Shrink volume

If you drag right border leftwards, the Unallocated space will be created at the right sides of C: drive.

C drive shrank

Step 3: Press Apply on top left to execute.

Shrink volume to create new partition on Server 2012

After shrinking system C drive, you’ll get Unallocated space which can be used to create new volumes.

Step 1: Right click the Unallocated space and select “Create Volume”.

Create volume

Step 2: In the pop-up window, click OK to use all Unallocated space, as well as the default settings. Instead, you can do these operations:

  1. Add label (name) to this new volume
  2. Select a drive letter
  3. Select File System and cluster size
  4. Select to create this drive as Logical or Primary
  5. Drag either border to change the partition size.

New volume settings

Step 3: Remember to click Apply to execute.

Shrink C drive to expand D or other volume

If you want to expand other partition by shrinking C drive, follow the steps:

Step1: Right click C drive and select “Resize/Move Volume”.

Shrink c drive

Step 2: In pop-up window, drag right border leftwards to shrink the system volume. Click OK and back to the main window.

Shrink system volume

C: drive shrank and 20GB Unallocated space created behind C drive.

C drive shrank

Step 3: Right click D: and select “Resize/Move Volume” again. In the pop-up window, drag the left border leftwards to hold the Unallocated space.

Extend D drive

Extend D drive

Step 4: Click OK and back to the main window, as you see the Unallocated space added into D drive. Click Apply on top left to execute, done.

D drive extended


To shrink C drive or system partition in Windows Server 2012 R2, you may use either built-in Disk Management or 3rd-party partition software. If you cannot shrink C drive or want to get better experience, I suggest use 3rd-party software.

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