CRITICAL - Storage Spaces: ReFS mirrored storage space will not free up space, related Defrag issues

Frequent Contributor

This is an issue introed in the build of Windows 10 1903, first reported 8 months before release.

I didn't thought this would be included in to Server 2022 LTSC since I have successfully worked on this to be fixed by the storage team in a Windows 10 Dev build.


I have a running SR with MS support for over 1 year now so the fix from Insider dev gets at least backported to 2004 and later. They declined to fix it for 1903, 1909 due to end of support policies.
Now this also affects an Server LTSC build for the first time it gets even more "spicy". 

Due a recent change of my Storage Space I had to "evacuate" all data from the Storage Space and found the same behaviour:



- deletion of files on the volume does not free up space (only ReFS mirrored volumes on Storage Spaced (not necessarily S2D, S2D was not tested). The space is shown as used on the Windows Explorer

- deletion of files on the volume does not free up space on the Storage Pool


affected OS:

Windows 10 Pro / Enterprise / EDU 1903, 1909, 2004, 20H1, 20H2, 21H1 (beta channel),

Windows Server SAC 1903 or later

Windows Server LTSC 2022 LTSC (21H2)


open SR: 120072921001646


this is not a local issue and can

Feedback Hub (Storage Spaces file deletion issue):


(possibly related Defrag issues with Storage Spaces)


11 Replies

I would rate this as critical because deletion of files will not free up space on the volume or storage spaces pool, so users can end up (and I did back then in Insider Dev) with an unuseable system.
The only workaround is to reformat the affected volumes with ReFS to free up the space on the Storage Pool.

Or to format the volume with NTFS to avoid the issue at all (not suitable imho, if one wants to use the benefits of ReFS, e.g. Hyper-V VHDX Creation, Snapshots, Citrix PVS merge etc.)


edit: Screenshots for Server 2022 Build 20324 attached

Is there anything I could provide to help you to fix this? It's a double benefit if you can und fix it based on the ReFS of Windows Insider Dev it will be also fixed in Windows 10.

Thank you very much for your reply.

Dear @Mary Hoffman @Elden Christensen @Prasidh_Arora 
unfortunately this or other "issues" reported during the Windows Server 2022 LTSC have not been caught before release. On some items it was not clear for participants of these have been reviewed and triaged and the actual outcome.

By all means Windows (Server) is a very complex product, and I appreciate all time you can spare on to get in touch with testers.

I hope you are still reading this community hub, despite officially 2022 is "RTM"

I would like to strongly recommend review the private fix.
It does affect Windows Server 2022 and all previous Win 10 Pro / Enterprise / Pro for Workstation, Windows Server version, builds starting from 1903.
In worst case users an customers could end up with a "full" Storage Pool and outtake if they cannot attach more disks (unneedlessly).

Both issues could even affect AzureStackHCI 20H2 eventually , as the fix in Windows Insider was made in b16268.

The private Fix KB (intended and basically tested by the MS team and confirmed by me for 2004) is KB900645.

The fix is supposed to address these issues (we are refine on defrag behaviour still)
Noted: this private fix has a better behaviour than the one that I originally contributed to in b16268

feedback hub:

REG: 120072921001646, Storage Spaces pool does not reclaim free space from deleted files

Thanks to @Susan Bradley for her help to create the escalation support case back in 07/2020:heavy_heart_exclamation:

Dear Windows Server team, is this sub still being read ?
cc @Cosmos Darwin @Elden Christensen @Mary Hoffman 

best response confirmed by K_Wester-Ebbinghaus (Frequent Contributor)

@K_Wester-Ebbinghaus yes, absolutely :smile:    Sorry for the delayed response, we have been internally discussing.  It sounds like you are already working with CSS support and they have already provided a private which resolves the issue.  That fix is now going into our servicing pipeline for release in a future monthly Cumulative Update.  We are targeting that fix for a cumulative update for WS2022 / AzS HCI 21H2, however I don't have a date for you at this time.  Continue working with your CSS contact. 




When will AzS HCI 21H2 hit insiders?
Win Srv 2022 Build 20348 is with insiders.
Azure Stack HCI, version 21H2 is now in Preview. Here's the link on how to opt-in to get the update:

Windows Server 2022 is now RTM and the final build is available. Here's a link to the blog that has links to the download on the eval center. Non-eval media is available on VSS (aka. MSDN):


@Elden Christensen thank for taking your time to reply Elden. I appreciate it a lot and gives me clarity that things will go the right route. 
If you can spare some there is other feedback with feedback of mine. I know you basically rule out GUI changes but basically think these could be small effort fixes with a good result for those that still need Server with GUI. I am a Server Core advocate, but well other vendors don't play nicely. Citrix is one of them demanding a GUI instead of Features on demand to support their legacy consoles. 
I want to hesistate to repost my requests here to keep it clean I am sure you will find them. Thanks for feedback (VSS, Server Manager Print Role, TLS etc) 

The vast majority of customers use the Desktop installation with Windows Server, it delivers the lowest OpEx and I'm all good with that... Server Core is an option for those who choose it, but do what's best for you. With that said, using the desktop for server management... is about management, and my previous comments were about using a server with desktop installed purely as a client is not a high priority. Such as running iTunes to stream music :) It's just a prioritization, as there are only so many dev's and so many hours in the day... but if you have feedback related to server management with the GUI, I'm all ears
Can you make Windows Admin Center, replace Server Manager when it comes to adding AND "Configuring" Roles & Features ???

Pretty Please & Thanks.

@Elden Christensen hello Elden I hear you and understand the mechanics how you triage. For now it would be great if the regressions with

- missing VSS in context menu (since 2012)

missing Printing console in Server Manager (since 2012)

Server Manager based version filtering (since 2019)

Powershell Domain level still points to Threshold (codename instead of version) (since 2016)

could be addressed.

All of these are minor code changes. The team managed to fix a more critical DSAC issue with wrong selection, I hope these glitches aren't asked to much for 2022 or 2019 if possible.

Otherwise WAC is doing great and you can check uservoice I am actively working on this to make it even better.