C drive is running out of disk space in Windows Server 2016.

I am running Windows Server 2016 on my server at work and the C drive is running out of space and has less than 100 megabytes left. This server is made the C drive 30 gigabytes and another D drive, 300 gigabytes. I am wondering if it is possible shrinking the D drive and expanding the C drive to make more room.

This is typical question on Windows Server 2016. Most of the server administrators encountered such problem that system C drive is running out of space or becomes almost full. Meanwhile, there is plenty of free space in D or other drives. In this case, you can extend C drive by shrinking the data drives. However, the first step when C drive runs out of space is freeing up disk space with Disk Cleanup or other tools. Because no partitioning software ensure 100% data safety while partitioning, it may cost a long time to repartition hard drive if there are large amount of files in this server.

First step – free up disk space

About freeing up space, I always suggest Windows built-in Disk Cleanup, because I have used it in most of the Windows editions MANY times. To me, it is trustable. Here I won’t introduce other ways such as using 3rd party software or deleting manually.

Steps to free up disk space with Disk Cleanup:

Step 1: Open Windows Explorer, right click C drive and select “Properties“.

Free up space

Step 2: Click “Disk Cleanup“, you may also click option to compress this drive to save more disk space.

Disk Cleanup

Step 3: In next window, click the check-box in front of the files you want to clean.

Select files

Step 4: Click OK and confirm this operation.


My test server is new installed, so there is little space can be reclaimed.

It is easy and fast to complete this task. However, some servers cannot reclaim much free space, the main reason C drive running out of space is not fill up by junk files, but too small disk partition. To save disk space, some people create the C drive 30GB – 50GB, it is too small. C drive of some factory server is not big enough, too. In this situation, you should complete the Second step to resize disk partition and increase C drive size.

Second step – increase C drive space

Different with other read-only applications, partition software will move files and modify the disk partition parameters, so a bad designed software or server hardware issue (such as power off, RAW or HDD) may cause data loss. So remember two points before resizing disk partitions:

  1. Select a reliable partition program.
  2. Back up the server before any operations.

Here I recommend aomei partition assistant, which integrated Enhanced Data Protection technology to keep operating system and data intact. Steps to expand C drive:

Step 1. Download this program, right click the drive that has enough free space and select “Allocate Free Space”.

Reallocate space

Step 2. In next window, type the amount of free space to take from this drive, and select C drive in the drop-down box.

Type amount

Step 3. Press Apply button on top left to proceed, done.

C drive extended

As long as there is free space in any drive of the same disk, you can use it to increase C drive.


When system C: drive is running out of space on Windows Server 2016, try to free up disk space with Disk Cleanup, and then increase C drive free space with server partition software.

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