Cannot shrink volume in Windows Server 2016

Published on: November 16, 2019

This article explains why unable to shrink volume in Windows Server 2016 and what to do if cannot shrink C drive with Server 2016 Disk Management.

If you forget to edit partitions while installing Operating System, system partition C occupies all available disk space. I that case, you can shrink C drive to create new volumes without starting over. If C drive is getting full, you can shrink D or other volume to expand it without losing data.

However, many people feedback that they cannot shrink volume D or unable to shrink C drive in Windows Server 2016 Disk Management. This article introduces possible reasons and what to do if Shrink Volume greyed out in Server 2016 Disk Management.

Why cannot shrink system C drive in Server 2016

The same with previous version, Windows Server 2016 has built-in Shrink Volume function in Disk Management tool. It helps decrease partition size without losing data and on the fly. However, both Shrink Volume and another Extend Volume functions have many restrictions.

There are 3 common reasons why unable to shrink C drive with Server 2016 Disk Management.

Reason 1: file system error

Cannot shrink C drive

As the screenshot shows, there's 7.53GB free space in C drive, but Disk Management gives no available space in the shrinking window.

In this case, follow the steps below to fix file system error:

  1. Press Windows and X together on the keyboard, click Command Prompt.
  2. Type chkdsk c:/v/f and press Enter in the command window. (simply replace c with d if you want to repair D drive)
  3. To system C drive, chkdsk will report cannot lock drive and ask you if schedule this volume to be checked the next time the system restarts. Type Y and press Enter.
  4. Restart server to repair.

Reason 2: not enough space

Error message

After clicking Shrink button, you may receive error message - "There is not enough space available on the disk(s) to complete this operation."

Disk Management gives maximum available space in the shrinking window by default. Before clicking Shrink button, if any Windows Update or other files saved into C drive, the available free space is less than calculated.

In this case, simply run Shrink Volume function again.

Reason 3: unmovable files

There's a tip in middle of the shrinking window - "You cannot shrink a volume beyond the point where any unmovable files are located."

For example: there's 40GB free unused space in C drive, if there are "unmovable" files located in block 3, Disk Management cannot shrink C: drive beyond this block to 1 or 2. Therefore, Disk Management only allow you shrinking C drive with free space in block 4. This is the reason why many people feedback that there's plenty of free space but Disk Management give little available space to shrink.

Unmovable files

Why unable to shrink data volume with Disk Management

To data volumes, there are the same reasons, but you are not likely to encounter this issue comparing with system partition C, because most of "unmovable" files are located in C drive.

The most common reason why cannot shrink data volume in Server 2016 Disk Management is because this partition is not supported.

In fact, only the partitions that are formatted with NTFS or without any file system (RAW) can be shrunk in Disk Management. As you see in the screenshot, drive D is a FAT32 partition, so Shrink Volume is grayed out.

In this case, you have to use 3rd-part software to shrink shrink.

Cannot shrink D

Comparing with Windows Disk Management, NIUBI Partition Editor has advantages while shrinking partitions:

Why cannot shrink volume D to expand C

Another common issue is that you cannot extend a volume after shrinking another one, no matter you want to shrink D to expand C drive, or shrink C to expand D drive.

Cannot extend volume

As you see, Extend Volume is greyed out for C and E drive after shrinking D. This is because:

  • Extend Volume only works when there's contiguous Unallocated space on the right side.
  • Shrink Volume can only make Unallocated space on the right.

The 20GB Unallocated space that shrunk from D is non-adjacent to C drive and is on the left side of E, therefore, Extend Volume is disabled.

No matter you cannot shrink volume in Windows 2016 server, or cannot extend volume by shrinking other one, follow the steps in the video. You just need to drag and drop on the disk map.

How to shrink C drive and expand other volumes:

Video guide

How to extend C drive by shrinking other volumes:

Video guide

Besides shrinking and extending partitions, NIUBI Partition Editor helps move, merge, copy, convert, defrag, hide, wipe partition, scan bad sectors and much more.