WSLimming

A PowerShell automation tool that compacts WSL2 ext4.vhdx virtual hard disk files to recover unused disk space.

The tool follows the Unix philosophy of doing one thing well - it's a single-purpose tool with minimal dependencies.

The Problem

WSL2 stores Linux distribution data in virtual hard disk files (ext4.vhdx). These files automatically grow as you add data, but they never shrink when you delete files or uninstall applications.

This leads to wasted disk space - even after cleaning up your WSL environment, the VHDX file retains its maximum size.

Quick Start

Requirements: Administrator privileges, PowerShell, WSL2

Option 1: Run directly (no clone required)

Open PowerShell as Administrator:

irm https://raw.githubusercontent.com/lib3yu/wslimming/refs/heads/main/wslimming.ps1 -OutFile wslimming.ps1; .\wslimming.ps1

Option 2: Clone and run

git clone https://github.com/lib3yu/wslimming.git
cd wslimming
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\wslimming.ps1

How It Works

┌─────────────────────────────────────────────────────────────────┐
│  1. Enumerate WSL distros from Windows Registry                 │
│  2. Prompt user to select a distro (if multiple installed)     │
│  3. Locate the ext4.vhdx file for the selected distro          │
│  4. [Optional] Analyze disk usage and package sizes            │
│  5. [Optional] Run fstrim to trim unused filesystem blocks     │
│  6. Shutdown WSL and compact the VHDX using DISKPART           │
└─────────────────────────────────────────────────────────────────┘

Pre-compaction Analysis

Before compacting, you can optionally run analysis to identify what's consuming space:

Analysis	Description	Availability
Space Analysis	Scans filesystem for large directories	All distros
Package Analysis	Shows largest installed packages	Debian/Ubuntu only

Why fstrim matters

Running fstrim before compaction marks unused filesystem blocks as free, allowing DISKPART to recover more space. This step is optional but recommended for maximum space recovery.

Usage Notes

• The script prompts for confirmation before each major step
• Compaction time depends on VHDX size and system performance
• The process cannot be interrupted once DISKPART compaction begins
• Always backup your data before running - see WARNING below

WARNING: This script modifies your WSL virtual disk files. While the compaction process is safe, backup your important data before proceeding.

Compatibility

Platform	Status
Windows 10	✅ Supported
Windows 11	✅ Supported
WSL2 distributions	✅ Supported
WSL1	❌ Not supported (different storage format)

License

MIT License - see LICENSE for details