Windows Server 2012 C: drive full solution

Updated on: June 5, 2019

The same with other Windows Operating System, Windows Server 2012 C drive is also getting full in some day, no matter you use physical hard disk or RAID arrays. When the system C: drive is full, it'll change to be red in Windows Explorer.

If you see this red bar or receive Low Disk Space warning, you'd better try to fix this issue as fast as possible. Otherwise, it may cause system stuck, server reboot unexpectedly or even crash.

In this situation, you may try to free up disk space with Server 2012 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 this issue annoyzing.

C drive is full

If you have not tried Windows Disk Cleanup utility, follow the steps:

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

This is the first step when system partition C is full in Windows Server 2012. By cleaning up, you can reclaim free disk space more or less. Thus, the server could keep running in the right way, furthermore, there is precious free space to install other tools.

However, it doesn't mean try all your best to get 1GB more free space. These space may be eaten up quickly by new generated junk files. You'd better expand C: drive as large as possible.

In most of the servers, there are other volume such as D with large amount of free space in the same hard disk. You can transfer part of unused 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 disk partitions with structure and other information on the right, available operations to highlighted disk or partition are listed on left or 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 drive D: and select "Resize/Move Volume", drag left border towards right in the pop-up window. (or enter an amount manually)

Shrink D

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 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 for servers. About resizing partitions, there is no difference if you use single hard disk, RAID 0/1/5 or other types. Remember: don't break array or do any operations to the RAID controller.