Besides creating new partition, Unallocated space can be used to extend other partition. You can get Unallocated space by deleting or shrinking a partition with Windows built-in Disk Management tool. By shrinking partition, you'll get Unallocated space without losing data (in most cases), of course it's much better than deleting partition. However, many people encounter the issue that Unallocated space can't be merged into C drive after shrinking D. In this article, I'll show you how to add Unallocated space to system C drive in Windows Server 2019.
Windows Server 2019 Disk Management has the ability to add Unallocated space to other partition, but it is useless in most cases. Because Disk Management can only add Unallocated space to the left contiguous partition.
As you see in the screenshot, the Unallocated space that shrunk from D: drive can only be added back to D, Extend Volume is disabled for both C: and E: drive.
Shrink Volume function can only make Unallocated space on the right while shrinking partition D, this Unallocated space is nonadjacent to C drive. This is the reason why many people feedback that they cannot add Unallocated space to C drive in Server 2019 Disk Management.
The only way to merge Unallocated space to C drive is by deleting partition D. Caution: don't do this if you installed programs to D drive.
Under some particular condition, Disk Management still cannot extend C drive even after deleting D.
If you have shrunk drive D with Disk Management, NIUBI Partition Editor can move Unallocated space from right of D to the left, then add Unallocated space to system partition C easily. To do this, just need to drag and drop on the disk map.
Steps to move and add Unallocated space to C drive in Windows Server 2019:
If you use any types of hardware RAID arrays such as RAID 0/1/5/10, don't break array or do any operation to raid controller, simply follow the steps in the video.
It is easy to add Unallocated space to system C drive in Windows Server 2019, but you'd better back up first and run safe partition software, because there's potential system/data damage risk while modifying disk partitions.
Better than other disk partition tools, NIUBI Partition Editor is much safer and faster because of the advanced technologies:
In few servers, there's no free unused space in other partitions on the same disk, some people ask whether it's possible to add Unallocated space to C drive from another disk. The answer is no. No software can transfer free/Unallocated space from another separated disk.
In this situation, there are 2 options to expand C drive for Server 2019:
As a disk management toolkit, NIUBI Partition Editor helps do many other operations to your server.