Diskpart Extend Volume C Drive in Windows Server 2016

by John, Updated on: July 25, 2022

C drive low disk space is common issue in Windows 2016 server. In that case, it can't be better if you can increase C drive free space without wasting a long time to recreate partitions and restore everything. Many administrators like to use command line tool. To extend Server 2016 partition, there is indeed a native diskpart command tool. However, because of many restrictions, it is not the best tool. This article introduces how to extend C: drive with diskpart in Windows Server 2016, and the shortages to extend volume with diskpart cmd in Server 2016.

How to extend system C: drive with diskpart in Server 2016

It is easy to extend C: drive with diskpart in Windows Server 2016, but firstly you must delete the contiguous partition D (or E:), follow the steps below:

  1. Transfer all files in drive D (or E in your server) to other place.
  2. Press Windows + R together on the keyboard, type diskpart and press Enter.
  3. Type list volume and press Enter in diskpart.exe command prompt window.
  4. Type select volume D and press Enter. (D is drive letter or number of the right contiguous partition.)
  5. Type delete volume and press Enter.
  6. Type select volume C and press Enter.
  7. Type extend and press Enter.

In a short time, diskpart reports successfully extended the volume. Type list volume again, as you see, my C drive is increased from 40GB to 110GB.

  • If you extend C drive with diskpart without deleting D, you'll receive error "There is not enough usable free space on specified disk(s) to extend the volume."
  • Don't delete drive D if you installed programs or any Windows services in it.

Diskpart extend C

Shortages to extend partition with diskpart in Windows Server 2016

Diskpart has another shrink command, why not shrink drive D to expand C? Because it doesn't work. When you extend C drive with diskpart in Windows Server 2016 after shrinking D, you'll receive error message that there is not enough usable free space.

In diskpart command prompt window, type help extend and you'll see the syntax and restrictions of extend command.

Diskpart extend limitations

Server 2016 diskpart extend command only works when your disk partition meet following requirements:

  1. The partition that you want to extend must be formatted with NTFS file system.
  2. There must be "Unallocated" space immediately follow (contiguous and on the right side of) the partition that you want to extend.
  3. This partition and Unallocated space must be on the same disk.

After shrinking D: drive, Unallocated space is on the right of D rather than C, therefore, extend command doesn't work. This is the reason why you must delete adjacent D drive to get Unallocated space behind C drive . If there is no right contiguous partition or you can't delete it, you cannot extend partition with diskpart in Windows Server 2016.

If you have shrunk drive D, follow the steps to move Unallocated space to the left and add to C drive.

Better way to extend volume in Windows Server 2016

Better than diskpart command, NIUBI Partition Editor can make Unallocated space on either left or right, so there's no need to delete partition, other advantages include:

Download NIUBI Partition Editor and follow the steps in the video to shrink and extend volume in Windows 2016 server.

How to extend C: drive by shrinking other volume:

Video guide

How to extend D: drive by shrinking other volume:

Video guide

  • If you want to extend non-adjacent volume, there's an additional step to move partition.
  • Steps are the same no matter you run physical server with SSD, HDD, RAID or virtual server in VMware/Hyper-V.

Better than other tools, NIUBI Partition Editor has advanced technology to protect system and data.

Besides shrinking, extending, moving and copying disk partitions, NIUBI Partition Editor helps merge, convert, defrag, wipe, optimze, hide partition, scan bad sectors and much more.