Add space to C drive in Windows Server 2012

Updated on: November 16, 2019

This article introduces how to add space to C: drive in Windows Server 2012 R2. 3 ways to add space to system partition with free unused or Unallocated space.

Add Unallocated space to C drive

There are two kinds of disk space that can be added into C drive to increase partition size: Unallocated and unused space inside a partition.

After deleting a partition, all its disk space will be converted to Unallocated. By shrinking a partition, part of unused space will be converted. No matter in which way, finally you'll add Unallocated space to C: drive (or other partition). Obviously, it's better to get Unallocated space by shrinking, so you won't lose data in it.

In Windows Server 2012 native Disk Management tool, there is Shrink Volume function to make Unallocated space and Extend Volume to combine Unallocated space into partition. Thus, many server administrator try to add more space to C drive by shrinking D. Actually, it is impossible with Disk Management if you want to increase C: drive space in this way.

Extend volume disabled

Shrink Volume can only make Unallocated space on the right side, Unallocated space can't be combined to the right contiguous or any non adjacent partitions with Extend Volume function.

So, Extend Volume is disabled for both C: and E: drive after shrinking D.

In most of servers, there are programs or some Windows services running from drive D, so you can't delete it to get adjacent Unallocated space.

In this situation, you need to run NIUBI Partition Editor to move Unallocated space to the left side and then add into C drive.

Watch the video how to add Unallocated space to C: drive in Windows Server 2012:

Video guide

Add unused space to C drive

If you have not shrank D or other partition in Server 2012 Disk Management, it's better to shrink with NIUBI, then Unallocated space can be made on the left side without moving.

Steps to add space to C: drive in Windows Server 2012:

Step 1: Download NIUBI Partition Editor, right click drive D: and select "Resize/Move Volume", drag left border towards right in the pop-up window. (or enter an amount manually)

Shrink D

Then 20GB unused space of D is converted to Unallocated on the left side.

Drive D shrank

Step 2: Right click system partition C: and select "Resize/Move Volume" again, drag right border towards right in the pop-up window.

Extend C drive

Then the 20GB Unallocated space is added into C drive.

C drive extended

Remember to click Apply to take effect, otherwise, the real disk partitions won't be changed.

Watch the video how to add space to system C: drive in Windows Server 2012 from other volumes:

Video guide

Add space to C drive with other disk

If some servers, Disk 0 is small and there is not plenty of unused space in other partitions (or even no other volume) in the same disk. In that case, no software can shrink partition in other separated disk (such as Disk 1) and add space to C drive (in disk 0). Because a hard disk is physical unit and the size is fixed.

In this situation, you can clone Disk 0 to another larger one and extend C drive with extra disk space. After that, replace Disk 0 or change BIOS to boot from the larger disk.

How to add space to C: drive in Windows Server 2012 by cloning:

Video guide

In Summary

Windows built-in Disk Management tool is useless in most cases. To add more space to system partition C, NIUBI Partition Editor is much better. It provides several ways according to your disk partition structure.

Comparing with other software, it is safer and faster because of its unique technologies: