Solution - System C Drive Is Full in Windows Server 2016

by Allen, Updated on: July 19, 2022

The same with previous versions, Windows Server 2016 system C: drive also runs out of space. Many people feedback that C drive is getting full in Windows 2016 server. To data partitions, it is easy to transfer files or change some settings, but it is complicated to the system partition. To many server administrators, C drive full is annoying, because Microsoft doesn't provide any solution except Disk Cleanup to help free up disk space. Some people did clean up disk but C drive becomes full again shortly. This article introduces a 3-step solution to fix Windows Server 2016 C drive full issue fast and easily.

Step 1 - Clean up C drive to reclaim disk space

It is dangerous if C drive is getting almost full, in this situation, you cannot install important Windows Update. Server could stuck, reboot unexpectedly or even crash. Therefore, you'd better fix this issue as fast as possible.

The first step is cleaning up C drive to reclaim disk space, then there will be some free space again in the system partition, so this server could keep running in the right way.

To do this, Windows Server 2016 has native Disk Cleanup tool, which is easy to use, runs fast and is able to remove many types of junk and unnecessary files safely.

How to fix C drive full in Windows Server 2016 by cleaning up disk:

  1. Press Windows + R together on the keyboard, type cleanmgr and press Enter.
  2. Select C: drive in the drop-down list.
  3. Wait Disk Cleanup utility to scan removable junk files and calculate space.
  4. Click the check-boxes in front of the files that you want to remove.
  5. Click OK to confirm and execute. (The time depends on the server performance and the amount of junk files.)

My test server is new installed, so I cannot reclaim large amount of disk space. But to the servers that never or have not free up space for a long time, you may get several gigabit free space by Disk Cleanup.

Disk cleanup

If you cannot get at least 20GB free space after cleaning up disk, you'd better add more free space to C drive from other partition. Otherwise, free space will be eaten up quickly by new generated junk files.

Step 2 - Expand C drive with free space in other volumes

The most effective way to fix Windows Server 2016 C drive full issue is adding more free space to C drive from other partition.

To do this, Windows native Disk Management cannot help you, although there are Shrink and Extend Volume functions to help resize disk partition. As you see in the screenshot, Extend Volume is disabled for C and E drive after shrinking D.

Cannot extend volume

Learn why cannot extend C drive in Server 2016 with Disk Management.

Third party software can help you move free space on a disk, but few are safe enough. Nobody likes to see system damage or data loss. Therefore, you'd better back up first and run safe partition software. Better than other tools, NIUBI Partition Editor has powerful technologies to protect your system and data:

Download NIUBI Partition Editor and follow the steps in the video to increase C drive free space for Server 2016:

Video guide

As you see in the video, you can shrink other data drives on the same disk to get Unallocated space and add into C drive. To do this, you just need to drag and drop on the disk map. Operating System, programs and anything else keep the same (except partition size).

The steps are the same no matter you use physical disk, any types of hardware RAID arrays or virtual disk in VMware/Hyper-V virtual machine.

After expanding C drive, there will be plenty of free space again, this step is very important to help fix C drive full in Windows Server 2016, especially when C drive is created small or you cannot reclaim large amount of free space with Disk Cleanup utility.

Step 3 - Optimize server settings

To completely fix system C drive full in Windows 2016 server, you need the final step to optimize server settings:

  1. Install programs to a separate partition such as D.
  2. To the installed programs, change the default output path to other large partitions.
  3. Run Windows Disk Cleanup monthly to delete new generated junk files.

If the system disk is small and there is not enough free space in all partitions, you'd better replace it with larger one. NIUBI Partition Editor can help you clone disk partition to migrate Operating System and data. Besides shrinking, extending and clone disk partition, it helps you do many other operations.