Diskpart extend volume in Windows Server 2016

Published on: November 16, 2019

This article introduces how to extend partition with diskpart in Windows Server 2016, and alternative method if you cannot extend system C drive with diskpart command on Server 2016.

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 partitions, 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 alternative method when you cannot extend partition with diskpart.

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 right contiguous partition (D:), follow the steps below:

  1. Transfer all files in drive D to other partition manually.
  2. Press Windows and 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 command

Diskpart has another shrink command, why not shrink drive D to expand C? Because it doesn't work. When you run extend command for C drive in Windows Server 2016 after shrinking D, you'll receive the same 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 free 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 drive D, Unallocated space is on the right of D rather than C, therefore, extend command doesn't work. This is the reason why deleting D to get right contiguous Unallocated space. 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 next 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 side, 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 shrink partition and extend another 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.

Besides shrinking, extending, moving and copying disk partitions, NIUBI Partition Editor helps merge, convert, defrag, wipe, hide partition, scan bad sectors and much more. Better than other software, it has innovative technologies to protect system and data.

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