Windows Server 2025 runner images seem to have significantly less disk space after `D:` drive removal

[jieyouxu]

Description

Hi, we are observing that Windows Server 2025 runner images (20250708.1.0) seem to have significantly less available disk space after the D: drive removal:

Filesystem            Size  Used Avail Use% Mounted on
C:/Program Files/Git  150G  117G   33G  79% /

On the same image version, but prior to the D: drive removal, Windows Server 2025 20250708.1.0 images had

Filesystem            Size  Used Avail Use% Mounted on
C:/Program Files/Git  150G  113G   38G  76% /
D:                    150G   11G  140G   7% /d

140 GB of additional disk space through the availability of the D: drive.

Related, in Windows Server 2022 images (e.g. 20250710.1.0) that still has the D: drive setup,

Filesystem            Size  Used Avail Use% Mounted on
C:/Program Files/Git  256G  163G   93G  64% /
D:                    150G  3.4G  147G   3% /d

D: drive offers 147 GB of extra disk space.

After the D: drive was removed from Windows Server 2025 runner images, they only by default have ~33GB of disk space available. This is causing uncached LLVM + rustc toolchain builds for us to fail due to running out of disk space.

The available disk space question/concern was also echoed by @lazka in #12416 (comment) in [Windows Server 2025] image will no longer have D:/ drive accessible to users from 2025-07-14 #12416:

What will this change mean for disk space available to the job? Currently D: has 147GB of free space available, while C: only has 29GB.

But I don't think it was ever answered.

Questions

Is the reduction in disk space intentional?

Platforms affected

• Azure DevOps
• GitHub Actions - Standard Runners
• GitHub Actions - Larger Runners

Runner images affected

• Ubuntu 22.04
• Ubuntu 24.04
• macOS 13
• macOS 13 Arm64
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Image version and build link

Image: windows-2025
Version: 20250708.1.0

https://github.com/rust-lang/rust/actions/runs/16339294682/job/46157832226?pr=143684

Is it regression?

Yes, prior to D: drive being removed, there were way more disk space so uncached LLVM builds could succeed (https://github.com/rust-lang/rust/actions/runs/16262531937/job/45910951990)

Expected behavior

Either:

• Available disk space is roughly preserved on the Windows Server 2025 runner images after D: drive is removed, or
• It is explicitly clarified that the reduction in disk space is intentional. Or better, what disk space availability should users expect for these runner images?

Actual behavior

Available disk space is significantly reduced without explicit clarification.

Repro steps

Any larger builds using Windows Server 2025 images. This seems related to D: drive removal, not the exact runner image version.

[jieyouxu]

Related, will D: drive be removed from Windows Server 2022 images too? We're currently attempting to use that as a short-term workaround for this disk space problem on Windows Server 2025 images.

[jieyouxu]

UPD: looks like the docs are https://docs.github.com/en/actions/how-tos/writing-workflows/choosing-where-your-workflow-runs/choosing-the-runner-for-a-job#standard-github-hosted-runners-for-public-repositories

where the guaranteed storage space is (at the minimum) 14GB? So I suppose this isn't technically a breakage?

(This was quite hard to discover.)

[akilesh-amaran]

Hi @jieyouxu ,
Thank you for bringing this issue to our attention. We will look into this issue and will update you after investigating

[subir0071]

Hi @jieyouxu - Please feel free to fall back to windows-2022 runners as the D: is still available there.

As documented here, Github pledges a minimum 14GB pr standard runners.

A more long-term solution could be to look for using larger runners.

[lazka]

If anyone wants to make some space by deleting things, I've created ncdu files of the current runner images here: https://github.com/lazka/gha-runner-images-ncdu/releases/tag/2025-07-17 (explore locally via ncdu -f windows-2025-C.json for example)

I wonder if the 6GB C:/Windows/Installer could be cleaned up for example. Or on the arm image there are 10GB of random temp files, and things like the Epic Games Launcher :D It looks like it was copied from someones workstation (I know, I know, that image is not managed by GitHub..)

[jieyouxu]

As documented here, Github pledges a minimum 14GB pr standard runners.

A more long-term solution could be to look for using larger runners.

Thanks, I'll close this as not-a-bug as it follows the pledge :)