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"Available shrink space too small despite plenty of free space (unmovable files issue)"

sercan oğuz 0 Reputation points
2025-08-04T17:44:40.8166667+00:00

Hi there,

I'm trying to shrink my C: drive using Windows Disk Management, but the available shrink space is extremely limited — even though I have more than 390 GB of free space on the disk.

When I run:


defrag C: /A /U /V

It tells me:

You do not need to defragment this volume.

But in the report, I see:

Unmovable files and folders = 8

Total free space = ~395 GB

Largest free space block = ~42 GB

🧱 Background:

I had previously installed Ubuntu via VirtualBox, but I have deleted the VM and VirtualBox completely. Still, I can't shrink the partition more than a few GB.

❓ Questions:

What are these "unmovable files" exactly and how do they limit shrink operations?

Is there any safe method to temporarily disable or move them (like hibernation, pagefile, or restore points)?

Are there any Microsoft-recommended tools or procedures to bypass this limitation?

Could using third-party tools (like AOMEI, Defraggler) be dangerous or does Microsoft have official alternatives?

Any help or guidance would be really appreciated. Thanks in advance!Hi there,

I'm trying to shrink my C: drive using Windows Disk Management, but the available shrink space is extremely limited — even though I have more than 390 GB of free space on the disk.

When I run:


defrag C: /A /U /V

It tells me:

You do not need to defragment this volume.

But in the report, I see:

Unmovable files and folders = 8

Total free space = ~395 GB

Largest free space block = ~42 GB

🧱 Background:

I had previously installed Ubuntu via VirtualBox, but I have deleted the VM and VirtualBox completely.
Still, I can't shrink the partition more than a few GB.

❓ Questions:

What are these "unmovable files" exactly and how do they limit shrink operations?

Is there any safe method to temporarily disable or move them (like hibernation, pagefile, or restore points)?

Are there any Microsoft-recommended tools or procedures to bypass this limitation?

Could using third-party tools (like AOMEI, Defraggler) be dangerous or does Microsoft have official alternatives?

Any help or guidance would be really appreciated. Thanks in advance!

Windows for business | Windows Server | Storage high availability | Other
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  1. Nam Bui (WICLOUD CORPORATION) 80 Reputation points Microsoft External Staff Moderator
    2025-08-14T06:20:09.13+00:00

    Hi Sercan,

    Thank you for posting your question on the Microsoft Windows Forum. This is a common issue that trips up a lot of users, even when there's plenty of free space on the drive.

    Why it happens:

    Windows Disk Management can only shrink a partition up to the last unmovable file. These include:

    • Pagefile.sys (virtual memory)
    • Hiberfil.sys (hibernation)
    • System Restore points
    • Master File Table (MFT) and its metadata
    • Other system files locked by Windows

    ---> So even if you have 390+ GB free, if there's an unmovable file sitting near the end of the partition, Windows won't shrink past it.

    Here are steps to increase shrinkable space:

    1. Disable Hibernation Run this in Command Prompt (Admin): 
         powercfg -h off
    2. Temporarily disable the pagefile
      • Go to System Properties > Advanced > Performance Settings > Advanced > Virtual Memory
      • Set it to “No paging file” for C:
      • Restart your PC
    3. Turn off System Restore
      • Open System Protection tab in System Properties
      • Disable protection for C:
    4. Run Disk Cleanup Use cleanmgr to remove system files and temp data.
    5. Optimize the drive Run dfrgui and optimize the C: drive. This may help move some files.
    6. Check Event Viewer Open Event Viewer > Windows Logs > Application Look for Event ID 259 from “defrag” — it may tell you which file is blocking the shrink.

    Third-party tools: Both AOMEI Partition Assistant and Defraggler are generally considered safe and widely used by IT professionals and home users alike.

    • AOMEI Partition Assistant is praised for its intuitive interface and powerful features like resizing, merging, cloning, and OS migration. It’s especially helpful when Windows Disk Management fails due to unmovable files1.
    • Defraggler, developed by the makers of CCleaner, is a trusted disk defragmentation tool that works with both HDDs and SSDs and supports NTFS/FAT32 file systems2.

    ⚠️ Caution: Always back up your data before using any third-party tool

    Hope this helps!

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