WSL2 Disk Shrinker

Because Tux doesn't need all that empty space!

Features • Quick Start • Intune Deployment • Troubleshooting

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The Problem

WSL2 uses VHDX (Virtual Hard Disk) files that grow automatically as you use them, but never shrink when you delete files. Over time, these virtual disks can consume tens of gigabytes of unnecessary space on your drive.

This tool fixes that by automatically compacting all WSL2 VHDX files across all users on a machine.

Features

• Auto-discovery - Finds all WSL2 distributions (Microsoft Store & custom installations)
• Multi-user support - Scans all user profiles when running as SYSTEM
• Dual optimization - Uses Hyper-V Optimize-VHD with diskpart fallback
• Intune-ready - Pre-packaged .intunewin file included
• Detailed logging - Full audit trail in C:\ProgramData\WSL2Shrinker\Logs\
• Safe execution - Gracefully handles edge cases and missing prerequisites
• User notifications - Toast notifications before/after optimization
• Non-disruptive mode - Option to skip if WSL is actively running
• Grace period - Configurable warning time before WSL shutdown (default: 30s)

Quick Start

Option 1: Download Pre-built Package

Download Install-WSL2Shrinker.intunewin and deploy via Intune.

Option 2: Run Manually

# Run as Administrator
.\Shrink-WSL2Distributions.ps1

Option 3: Build Your Own Package

IntuneWinAppUtil.exe -c ".\\" -s Install-WSL2Shrinker.ps1 -o ".\output"

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Intune Deployment

Step 1: Download the Package

Download the pre-built package from this repository:

• output/Install-WSL2Shrinker.intunewin

Or build it yourself using the Microsoft Win32 Content Prep Tool.

Step 2: Create Win32 App in Intune

1. Navigate to Microsoft Intune admin center
2. Go to Apps → Windows → Add
3. Select Windows app (Win32) and click Select

Step 3: App Information

Field	Value
Name	WSL2 Disk Shrinker
Description	(See below)
Publisher	IT Department

Recommended Description for Intune:

🐧 WSL2 Disk Optimizer

Automatically reclaims unused disk space from Windows Subsystem for Linux (WSL2) virtual disks.

📦 What it does:
• Finds all WSL2 distributions on your system
• Compacts VHDX virtual disk files to free up space
• Typically saves 2-20 GB depending on usage

⚠️ IMPORTANT:
• WSL will be temporarily SHUT DOWN during optimization
• Save your work in any running Linux terminals before this runs
• You will receive a notification 30 seconds before shutdown
• All WSL sessions will be closed automatically

📋 After completion:
• Your WSL distributions remain intact
• All data is preserved
• WSL restarts normally on next use

📁 Logs: C:\ProgramData\WSL2Shrinker\Logs\

Field	Value
App Version	1.0
Category	Computer Management
Information URL	https://github.com/rafriedmann/wsl2-shrinker
Privacy URL	(optional)
Developer	(optional)
Owner	(optional)
Notes	Reclaims unused disk space from WSL2 virtual disks
Logo	Upload icon.png from this repository

Step 4: Program Settings

Choose ONE of the following install command options based on your needs:

Option A: User-Friendly Mode (Recommended)

Shows toast notification, gives user 30 seconds warning before WSL shutdown.

powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -File Install-WSL2Shrinker.ps1

Option B: Non-Disruptive Mode

Skips optimization if WSL is currently running. Will retry on next Intune sync.

powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -File Install-WSL2Shrinker.ps1 -SkipIfRunning

Option C: Silent Mode

No notifications, immediate shutdown. Use for off-hours deployment.

powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -File Install-WSL2Shrinker.ps1 -Silent

Field	Value
Install command	(Choose from options above)
Uninstall command	powershell.exe -ExecutionPolicy Bypass -File Uninstall-WSL2Shrinker.ps1
Install behavior	System
Device restart behavior	No specific action
Return codes	Use defaults (0 = Success, 1707 = Success, 3010 = Soft reboot, 1641 = Hard reboot, 1618 = Retry)

Step 5: Requirements

Field	Value
Operating system architecture	64-bit
Minimum operating system	Windows 10 1903
Disk space required	No
Physical memory required	No
Minimum number of logical processors	No
Minimum CPU speed required	No

Optional Requirement Script (to only target devices with WSL installed):

# Check if WSL is installed
if (Get-Command wsl.exe -ErrorAction SilentlyContinue) {
    Write-Output "WSL is installed"
    exit 0
} else {
    Write-Output "WSL is not installed"
    exit 1
}

Step 6: Detection Rules

Field	Value
Rules format	Use a custom detection script
Script file	Upload Detect-WSL2Shrinker.ps1
Run script as 32-bit process	No
Enforce script signature check	No

The detection script checks if the tool ran within the last 30 days. Modify $MaxAgeDays in the script to change this interval.

Step 7: Dependencies & Supersedence

• Dependencies: None required
• Supersedence: None required

Step 8: Assignments

Assign to your target groups:

Assignment Type	Recommendation
Required	Assign to device groups with developer machines
Available	Make available in Company Portal for self-service
Exclude	Exclude servers or machines without WSL

Recommended Filter (optional):

(device.deviceOwnership -eq "Corporate") and (device.operatingSystemVersion -contains "10.0.1")

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Files Included

File	Description
Shrink-WSL2Distributions.ps1	Main PowerShell script that performs the optimization
Install-WSL2Shrinker.ps1	Intune installer wrapper
Detect-WSL2Shrinker.ps1	Intune detection script (checks 30-day interval)
output/Install-WSL2Shrinker.intunewin	Pre-built Intune package
icon.svg / icon.png	Application icons

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How It Works

┌─────────────────────────────────────────────────────────────┐
│                    WSL2 Disk Shrinker                       │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  1. 🔍 Discover all WSL2 distributions                      │
│     └─ Registry scan + Package folder search                │
│                                                             │
│  2. 📁 Locate VHDX files                                    │
│     └─ %LOCALAPPDATA%\Packages\*\LocalState\ext4.vhdx      │
│     └─ Custom paths from HKCU/HKLM Lxss registry           │
│                                                             │
│  3. 🛑 Shutdown WSL                                         │
│     └─ wsl.exe --shutdown                                   │
│                                                             │
│  4. 📦 Compact each VHDX                                    │
│     └─ Primary: Optimize-VHD -Mode Full                     │
│     └─ Fallback: diskpart compact vdisk                     │
│                                                             │
│  5. 📝 Log results & set registry marker                    │
│     └─ HKLM:\SOFTWARE\WSL2Shrinker\LastRun                 │
│                                                             │
└─────────────────────────────────────────────────────────────┘

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Scheduling Options

Option 1: Intune Re-evaluation (Recommended)

The detection script returns "not installed" after 30 days, triggering a reinstall:

# In Detect-WSL2Shrinker.ps1
$MaxAgeDays = 30  # Change this value to adjust frequency

Option 2: Scheduled Task

Deploy a separate scheduled task for more frequent execution:

$Action = New-ScheduledTaskAction -Execute "powershell.exe" `
    -Argument "-ExecutionPolicy Bypass -File C:\Scripts\Shrink-WSL2Distributions.ps1"
$Trigger = New-ScheduledTaskTrigger -Weekly -DaysOfWeek Sunday -At 3am
$Settings = New-ScheduledTaskSettingsSet -RunOnlyIfIdle -IdleDuration 00:10:00
Register-ScheduledTask -TaskName "WSL2 Disk Shrinker" -Action $Action `
    -Trigger $Trigger -Settings $Settings -User "SYSTEM" -RunLevel Highest

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Logging

Log Location: C:\ProgramData\WSL2Shrinker\Logs\

Log Format: WSL2Shrinker_YYYYMMDD.log

Sample Log Output:

[2024-01-15 10:30:00] [Info] ========== WSL2 Disk Shrinker Started ==========
[2024-01-15 10:30:00] [Info] Running as: SYSTEM
[2024-01-15 10:30:00] [Info] Elevated: True
[2024-01-15 10:30:01] [Info] Found 3 WSL2 distribution(s)
[2024-01-15 10:30:01] [Info]   - Ubuntu (State: Stopped, Version: 2)
[2024-01-15 10:30:01] [Info]   - Debian (State: Stopped, Version: 2)
[2024-01-15 10:30:01] [Info]   - docker-desktop-data (State: Stopped, Version: 2)
[2024-01-15 10:30:02] [Info] Found 3 VHDX file(s) to optimize
[2024-01-15 10:30:02] [Info] Total VHDX size before optimization: 45.32 GB
[2024-01-15 10:30:02] [Info] Shutting down WSL...
[2024-01-15 10:30:07] [Info] WSL shutdown complete
[2024-01-15 10:30:07] [Info] Processing: Ubuntu
[2024-01-15 10:30:07] [Info] Optimizing: C:\Users\john\AppData\Local\...\ext4.vhdx (Current size: 15.20 GB)
[2024-01-15 10:30:45] [Info] Optimization complete. New size: 8.50 GB (Saved: 6860.00 MB)
...
[2024-01-15 10:32:15] [Info] ========== Optimization Summary ==========
[2024-01-15 10:32:15] [Info] Total space saved: 18.45 GB
[2024-01-15 10:32:15] [Info] ========== WSL2 Disk Shrinker Completed ==========

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Requirements

Requirement	Details
OS	Windows 10 version 1903+ or Windows 11
WSL	WSL2 (not WSL1)
Privileges	Administrator / SYSTEM
Optimization Tool	Hyper-V PowerShell module OR diskpart.exe

Enabling Hyper-V PowerShell Module (Recommended)

For best results, enable the Hyper-V PowerShell module:

# Windows 10/11 Pro, Enterprise, Education
Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-Management-PowerShell

# Or via DISM
DISM /Online /Enable-Feature /All /FeatureName:Microsoft-Hyper-V-Management-PowerShell

Note: The script falls back to diskpart if Hyper-V is unavailable.

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Troubleshooting

No VHDX files found

• Verify WSL2 is installed: wsl --list --verbose
• Ensure distributions are WSL version 2 (not 1)
• Check if running as SYSTEM can access user profile directories

Optimization failed

• Ensure WSL is completely shut down: wsl --shutdown
• Check if another process is locking the VHDX file
• Verify Hyper-V tools or diskpart are available
• Review logs: C:\ProgramData\WSL2Shrinker\Logs\

Detection always fails

• Ensure script runs with admin rights to write registry
• Check registry: HKLM:\SOFTWARE\WSL2Shrinker\LastRun
• Verify system clock is correct

Script runs but no space saved

• WSL2 disks may already be compact
• Run wsl --shutdown and manually delete unused files inside WSL first
• Consider running fstrim inside WSL before optimization:

  sudo fstrim -av

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License

MIT License - Feel free to use, modify, and distribute.

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_{Made with 🐧 for IT admins tired of bloated VHDX files}