Can't extend C

Cannot extend C drive on Windows Server 2019

After running the server for a period of time, you need to maintain disk drives, for example: create, delete, format, shrink and extend partition. To do this, Windows Server 2019 has its native Disk Management utility. C drive is very likely running out of space, because many types of files write into it every day. In this situation, many people try to extend C drive with Extend Volume functionality. But many people feedback that they cannot extend C drive because Extend Volume is grayed out.

In this article, I’ll explain why you unable to extend C drive in Windows Server 2019 Disk Management and show you the easiest way to solve this problem.

Why cannot extend C drive

Extend Volume only supports NTFS partition, so FAT32 and other types of partitions cannot be extended. All system C drive is NTFS format in Server 2019, so this issue does not exist. Another restriction of Extend Volume is that free space in Logical partition cannot be extended to Primary partition, but luckily this is restricted to MBR style disk. Windows Server 2019 format disk as GPT, so this limitation is no longer a problem.

The most common reason why Extend Volume is disabled for C drive is because no adjacent Unallocated space on the right side.

In my test server, there is no contiguous Unallocated space, of course I cannot extend C drive. Extend Volume is still disabled even if I shrank D and got some Unallocated space.

Can't extend C

Windows Server 2019 Disk Management can only generate Unallocated space on the right side when shrinking a volume, in addition, it has no “move volume” functionality to move the Unallocated space to behind C drive. So it can’t extend C drive with this space.

What to do if unable to extend C drive

Actually, it is very easy to solve this problem with disk partitioning software, however, not all 3rd-party software can accomplish this task well. Unreliable partitioning software could cause system damage and data loss while resizing and moving partitions. Thanks to its powerful 1 Second Rollback technology, NIUBI Partition Editor can ensure system and data intact. If any software internal error or hardware issue occur, it recovers to original status automatically and rapidly. So the server could back online without damage in a short time.

To solve the problem that can’t extend C drive:

  • If you have shrank D, NIUBI can move drive D to the right side of Unallocated space, and then Extend Volume is enabled for C drive.
  • If you have not shrank D, you can decrease D and generated Unallocated space on the left side directly.

Solution 1 – move partition to enable Extend Volume

Download NIUBI Partition Editor, the same with Disk Management, there is 20GB Unallocated space that is shrank from drive D.

Unallocated space

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

Move drive D

Drive D is moved to the right side of Unallocated space. (To change physical disk partitions, remember to click Apply on top left to execute.)

After it complete moving, Extend Volume is enabled for C drive.

Unallocated moved

You may continue to extend C drive with NIUBI: right click C drive and select Resize/Move Volume again, drag right border rightwards in the pop-up window.

Extend C drive

Unallocated space is combined to C drive.

C drive extended

Solution 2 – shrink D to extend C drive

It is also very easy to shrink D and generate Unallocated space behind C drive. Right click D and select Resize/Move Volume, drag left border rightwards in the pop-up window.

Shrink drive D

Unallocated space is generated, which can be used to extend C drive with Disk Management and NIUBI.

Unallocated moved

In Summary

Windows Server 2019 Disk Management has inherent limitations that cause you unable to extend C drive with the built-in feature. Luckily, NIUBI Partition Editor can help you solve this problem easily. If you cannot extend C drive in Server 2019 after shrinking D, simply run NIUBI to move drive D to the right side. If you have not shrank D, use Resize/Move Volume feature to generate Unallocated space on the left side. To extend C drive, you just need to drag right border in the pop-up window to combine the Unallocated space.

Download to try

Cannot/unable to extend c drive in Windows Server 2019.
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