Unable to extend system C drive in Windows Server 2008

Updated on: July 11, 2019

This article introduces why unable to extend C drive in Windows Server 2008 R2, what to do if Diskpart or Disk Management is unable to extend system partition.

Windows 2008 servers have been running for several years, many disk partitions run out of space, especially to system partition C. Many server administrators try to extend C drive without wasting a long time to recreate partitions and restore. However, many people feedback that they are unable to extend C drive in Windows Server 2008 with either diskpart command or Disk Management.

This article introduces the reasons and full solution.

Unable to extend C drive with Diskpart command

Diskpart works via command prompt, it is very easy and fast. However, unlike Disk Management, diskpart only lists single partitions with part of information. It doesn't display partition structure and any Unallocated space, so you may encounter more issue if you do not know everything about your disk partitions clearly.

I received error when extending C drive with diskpart the first time:

Diskpart error

Then I shrunk the contiguous volume D, however, the same error - The size of the extent is less than the minimum.

Unable with diskpart

Then I delete drive D, this time diskpart works.

Diskpart works

Type help extend and you'll see how diskpart Extend command works, the syntax and the limitations.

Extend command limitation

To be short:

Conclusion: Diskpart can only extend C drive when there is adjacent Unallocated space on the right. Unallocated space shrunk from other volume is nonadjacent to C drive, therefore, diskpart reports error. If there is no or you cannot delete the right contiguous partition, Diskpart is useless.

Unable to extend partition C via Disk Management

To enhance the disk partition management ability, Microsoft adds new Shrink Volume and Extend Volume in Server 2008 native Disk Management. However, the same with Diskpart command, Server 2008 Disk Management is unable to extend partition C by shrinking D or other drive.

As you see in my server, 20GB Unallocated space is shrunk from D, it is non-adjacent to C drive and on the left of E, so Extend Volume greyed out for these volumes.

If Disk Management can make Unallocated space on the left or move from right to the left, there is no such issue.

Extend greyed

If partition D is Logical, Server 2008 Disk Management still unable to extend C drive after deleting D.

Extend volume disabled

Unlike Primary partition, Logical partition will be converted to Free space after deleting, which is still part of the Extended partition.

In Server 2008 Disk Management, Unallocated space deleted from Primary partition can't be extended to any Logical partition. Free space deleted from Logical partition can't be extended to any Primary partition.

Diskpart has no such restriction, Free space deleted from D can be extended to C drive.

What to do when unable to extend system volume C

To solve this problem, you just need 1 step to move Unallocated space from right of D to the left. To accomplish this task, you need third party software such as NIUBI Partition Editor. Better than other tools, it is much faster and safer because of its unique 1 Second Rollback, Virtual Mode and Cancel-at-well technologies.

How to fix the issue - unable to extend C drive in Windows Server 2008 R2:

Download NIUBI Partition Editor and you'll see the main window with disk partition structure and other information. There is 20GB Unallocated space in Disk 0 that is shrunk from drive D.

NIUBI Partition Editor

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

Move drive D

Then Unallocated space is moved to the left.

Move Unallocated space

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

Extend C drive

Then Unallocated space is combined to C: drive.

Move Unallocated space

Click Apply on top left to execute. (All operations before this step only work in virtual mode)

If you have not shrunk volume D with Diskpart or Disk Management, you can make Unallocated space on the left directly without moving.

Watch the video guide:

Video guide

Unable to extend partition C with other disk

If there is no available free space, no software can extend C drive or other volumes in the same disk. In this situation, you have two choices according to your disk partition configuration.

1. If C drive is in VMDK or VHD:

Increase virtual disk size with the own tool of VMware or Hyper-V, then additional disk space will be shown as Unallocated on the end. Follow the step in the video to move and combine Unallocated space into C drive.

2. If you use physical disk or RAID array:

Copy to another larger disk and expand C drive with additional disk space.

Besides shrinking, moving, extending and copying disk partition, NIUBI Partition Editor helps you do many other management operations.