High Disk Usage in Docker on Windows

an easy way to reclaim the huge disk space used by docker on windows

Photo by Ian Taylor on Unsplash

Introduction

When installing Docker Desktop on Windows, a common issue that can arise is the failure of Docker to release disk space back to the operating system. To resolve this, additional steps are required to reclaim the disk usage in WSL.

1- Clean the Docker

First, you need to delete unused Docker images and stopped containers using the following command:

C:\> docker system prune -a
WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all images without at least one container associated to them
  - all build cache

Are you sure you want to continue? [y/N] y

Total reclaimed space: 20.38GB

2- Reclaim WSL disk usage

After running the above command, the disk usage is still not reduced! To reclaim the disk space used by WSL to the OS, you need to run the following commands in the CMD window:

C:\> wsl --shutdown
C:\> diskpart

In the DISKPART terminal, you have to enter the following commands (replace ${YOUR_USERNAME} with your username in the bellow command):

DISKPART> select vdisk file="C:\Users\${YOUR_USERNAME}\AppData\Local\Docker\wsl\data\ext4.vhdx"
DISKPART> attach vdisk readonly
DISKPART> compact vdisk
DISKPART> detach vdisk
DISKPART> exit

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