Windows Server 2012 C: drive full solution

by Jordan, Updated on: January 4, 2021

The same with other Windows PC and server, C drive is getting full in Windows Server 2012 (R2), too, no matter you use physical hard disk or RAID arrays. When the system C: drive is full in Server 2012 and R2, it'll change to be red in Windows Explorer.

When you see C drive showing full or receive Low Disk Space warning, you'd better try to fix this issue as fast as possible. Otherwise, it may cause server stuck, reboot unexpectedly or even crash.

In this situation, you may try to free up disk space with Server 2012 native Disk Cleanup or other tools, but generally speaking you cannot get large amount of free space, so C drive becomes full again in the near future. This is the reason why many people feedback that this issue is annoying.

C drive is full

First step to fix C drive full in Server 2012 (R2):

  1. Press Windows and R on your keyboard, type cleanmgr and press Enter.
  2. Select C: drive in the drop-down list and click OK.
  3. Click the check-box in front of the files that you want to delete and then click OK to execute.

If you receive error message Windows cannot find 'cleanmgr', you need to install or enable Disk Cleanup on Server 2012 first.

By cleaning up disk, you can reclaim free space for C drive, thus, the server could keep running in the right way, furthermore, there is precious free space to install other tools. However, these space will be eaten up quickly by new generated junk files. If you cannot reclaim over 10GB free space, you'd better add more free space to C drive from other partitions.

In most of servers, there are other volume with plenty of free space on the same hard disk. You can transfer part of free space from it into C drive with NIUBI Partition Editor. By this method, C drive will have plenty of free space again. No other operations are needed, Operating System, programs and everything else keeps the same with before.

Better way to fix C drive full issue in Windows Server 2012

Download NIUBI Partition Editor, you'll see all connected disks with partition structure and other information on the right, available operations to highlighted disk or partition are listed on left and by right clicking. As you see in my server, there are drive C, D and E are in Disk 0.

NPE Server

Step 1: Right click D: drive and select "Resize/Move Volume", drag left border towards right in the pop-up window. (Or enter an amount in the box of Unallocated space before.)

Shrink D

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

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 Unallocated space is combined into C drive.

C drive extended

Step 3: Click Apply on top left to execute.

If there is not plenty of free space in the adjacent partition D, you can shrink any non-adjacent volumes to enlarge C drive. Follow the steps in the video:

Video guide

If there is not plenty of free space in all other partitions, you can clone to a larger disk and enlarge C drive with extra disk space. Follow the steps:

Video guide

In Summary

When system C drive is full in Windows Server 2012 (R2):

  1. Try to reclaim disk space with native Disk Cleanup utility.
  2. Expand C drive as large as possible with NIUBI Partition Editor.
  3. Free up disk space monthly to delete new generated junk files.

Besides shrinking and extending partitions, NIUBI Partition Editor helps you merge, move, copy, convert, defrag, wipe, hide partition, scan bad sectors, etc.

Any difference with RAID or virtual machine?

It is very common to use hardware RAID arrays, VMware or Hyper-V virtual machine for servers. While resizing partitions and extending C drive, there is no difference. Remember: don't break array or do any operations to the RAID controller.