TIL - Reclaiming 160 GB from WSL2's Hidden Disk File
Today I Learned that deleting files inside WSL2 doesn't shrink your Windows disk usage — and one PowerShell command fixes it
TIL: Reclaiming 160 GB from WSL2’s Hidden Disk File
Today I Learned that deleting files inside WSL2 doesn’t shrink your Windows disk usage and one PowerShell command fixes it.
The Story
It started with a Windows notification: low disk space. My SSD was nearly full and I had no idea why.
Step 1 Cleaned the obvious suspects. As a JavaScript developer, I went straight for the usual culprits: Docker images, volumes, and mountains of node_modules. Cleared them all. The free space barely moved.
Step 2 Brought in a disk sniffer. Tools like WinDirStat or TreeSize Free visualize exactly what’s eating your disk. That’s when I found it a single ext4.vhdx file sitting quietly inside %LOCALAPPDATA%\Packages\..., consuming 240 GB.
Step 3 One PowerShell command later. The VHDX compacted from 240 GB → 80 GB. That’s 160 GB reclaimed in minutes.
What Is a VHDX?
A VHDX (Virtual Hard Disk v2) is a virtual disk format used by Hyper-V on Windows. WSL2 runs inside a lightweight Hyper-V VM, and it stores your entire Linux filesystem every file, permission, symlink, and inode inside a single ext4.vhdx file on your Windows drive.
The problem: the VHDX grows as you create files inside WSL, but it does not shrink automatically when you delete them. The space is returned to the Linux filesystem, but the Windows-side file stays the same size like a balloon that never deflates on its own.
The Fix
Prerequisites
- Windows 11 with WSL2 installed
- Hyper-V feature enabled (Pro/Enterprise, or Home with workaround)
- PowerShell running as Administrator
- A disk sniffer (WinDirStat, TreeSize) to locate your
ext4.vhdxpath
Step 1 Shut down WSL
The VHDX must not be in use during compaction.
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wsl --shutdown
Step 2 Navigate to the VHDX
The file lives inside your distro’s package folder. Replace the ... with your actual distro path.
Important Do not even hover that file from your explorer lol. IMO its better you restart your machine first and straight open powershell with administrator access.
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cd ~\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu..._...\LocalState
Step 3 Compact the disk
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Optimize-VHD -Path .\ext4.vhdx -Mode Full
-Mode Full removes all unused blocks the most thorough option. This is the command that dropped my VHDX from 240 GB to 80 GB.
Note: If
Optimize-VHDis not recognized, Hyper-V may not be enabled. Run the following in an elevated PowerShell, then restart:
Results
| Before | After | |
|---|---|---|
ext4.vhdx size | 240 GB | 80 GB |
| Space reclaimed | 160 GB (67% reduction) |
Key Takeaway
WSL2 silently accumulates disk usage over time especially for JavaScript developers cycling through node_modules and Docker layers.
Deleting files inside WSL frees Linux disk space, but not the Windows VHDX.
Run Optimize-VHD -Mode Full periodically, or whenever your SSD looks suspiciously full, to keep it honest.
Quick Reference
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# 1. Shut down WSL
wsl --shutdown
# 2. Go to your distro's LocalState folder
cd ~\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu..._...\LocalState
cd ~\AppData\Local\Docker\wsl\data\
# 3. Compact the virtual disk
Optimize-VHD -Path .\ext4.vhdx -Mode Full
Tested on Windows 11 with Ubuntu 22.04 on WSL2.