Extend C drive

Extend C drive on Windows Server 2019

When system C: drive is running out of space, you can increase its partition size without reinstalling Operating System and applications. As long as there is existing Unallocated space or free space inside of other drives, you can add these space to expand C drive. This article shows how to extend C drive in Windows Server 2019 without losing data.

Use right tool to extend system partition

Windows Server 2019 native Disk Management utility has built-in Shrink Volume and Extend Volume functionalities to re-size partitioned drives. However, you cannot extend C drive by shrinking D or other drives. The Unallocated space shrank from D is nonadjacent to C drive, so Extend Volume is greyed out when you right click C drive. You can get adjacent Unallocated space by deleting drive D to enable Extend Volume for C drive, but all installed programs and Windows service will be deleted. So to extend system C drive in Windows Server 2019, you need partitioning software.

Two points you should know before extending system partition in Server 2019:

  1. Unallocated space or free space of other drives should be in the same hard disk of C drive.
  2. There is system damage and data loss risk when you resizing partitions with software.

Many people including some server administrators do not know about this risks. Disk partition software is called data killer by the people that experienced computer disaster.

Why there is such kind of risk? To be short, all parameters of related disk, drive and files should be modified correctly when resizing disk partition. Some software internal error and hardware issue such as power failure could cause part of the parameters failed to be modified. If it happens, system and/or data will be damaged. So besides backing up the server, it is also very important to select a reliable partition software, otherwise, it costs a long time to restore everything. In addition, server is offline during this period.

As the safest partition software, NIUBI Partition Editor is integrated with innovative 1 Second Rollback technology to ensure system and data intact. If anything goes wrong while resizing partition and extending C drive, it roll back to original status automatically and rapidly. So the server could recover online without damage in a short time. If you want to change partition size for Windows server, NIUBI is the first choice.

Extend C drive with Unallocated space

As I said above, Windows Server 2019 built-in Disk Management has Shrink and Extend Volume feature to resize partition, some people try to shrink D and extend C drive. However, Extend Volume is disabled for C drive, leaving the Unallocated space in a puzzle. With NIUBI Partition Editor, you can expand C drive with Unallocated space, but first you should move the Unallocated space to behind C drive.

Steps to extend C drive in Windows Server 2019 with Unallocated space:

Download NIUBI Partition Editor, you’ll see all single partitions with detailed info on the top and all disk with partition layout on the bottom. There is 20GB Unallocated space that is shrank from drive D, I’ll walk you though how to add it to C drive.

Unallocated space

Step 1: Right click drive D and select Resize/Move Volume, in the pop-up window, drag middle position rightwards.

Move drive D

Unallocated space is moved to behind C drive.

Unallocated moved

Step 2: Right click C drive and select Resize/Move Volume again. Drag right border rightwards in the pop-up window.

Extend C drive

C drive is extended to 59.4GB by adding the Unallocated space.

C drive extended


  • All operations you do will be listed as pending on bottom left corner, you can preview or click Undo on top left to cancel. Physical disk partitions won’t be changed until you click Apply to confirm.
  • The pending operations with  can be done in Windows without server interruption.

Expand C drive by shrinking other drives

In most of the server computers, there is no such existing Unallocated space, but it doesn’t matter, you can extend C drive by taking free space from other partitions in the same disk.

In my test server, drive D is almost empty, so I can transfer part of free space into C drive.

NIUBI Main window

Steps to expand C drive in Windows Server 2019 with free space:

Step 1: Right click drive D and select Resize/Move Volume, in the pop-up window, drag left border rightwards.

Shrink drive D

Some Unallocated space is generated on the left side of D drive.

Drive D shrank

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

Extend C drive

C drive is extended by combining the Unallocated space.

If there is not plenty of free space in the adjacent drive D, you can get free space from any other drives in the same disk.

Watch the video how to extend C drive in Windows Server 2019:

In Summary

To resize and extend system C drive on Windows Server 2019, the built-in Disk Management is useless, so you need third party partition software which is safe and reliable. Because of its unique rollback technology, NIUBI Partition Editor can extend system partition and data drive keeping everything intact. Any Unallocated and free space in the same disk can be used to extend C drive.

Download to try