Moving Docker Data – Volumes, Images, and More

Drive C: is Docker’s preferred drive. If the hard drive is full, you can move the Docker data to another hard drive.

The ext4.vhdx is a virtual hard drive. Think of it as a sealed container that houses a complete Linux file system (ext4). In the world of Docker Desktop for Windows, this file is the “heart” of the system.

Here is the exact content:

1. Docker Images

This is usually the biggest chunk. Every time you run docker pull or download an image for Paperless (e.g., Redis, Postgres, Tika), it ends up in this file.

• The base operating systems of the containers (e.g., Debian, Alpine).
• The installed software (Python, Java, etc.).

2. Docker Volumes (Your data!)

This is the most important part of your paperless project. If you have defined volumes in your docker-compose.yml that do not refer to a Windows folder (so-called “named volumes”), they are located in this file.

• The Paperless database.
• The indexed documents.
• Configurations.

3. Container write layers

Every running container has a “writable layer.” When a program in the container writes a log file or stores temporary data, these bits and bytes end up in the ext4.vhdx.

4. The WSL operating system itself

Docker on Windows requires a mini Linux to function at all. The system files for this “Docker backend Linux” are also located there.

5. The old way

The old method no longer works in the newer Docker Desktop files. Commands such as those via PowerShell

wsl --export docker-desktop-data D:\DockerBackup\docker-data.tar

no longer work.

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The new way—that is the new method

Starting with Docker Desktop for Windows ≥ approx. 4.19, the new method applies..

About Docker Desktop GUI (BEST solution)

1. Docker Desktop öffnen
2. ⚙ Settings
3. Resources → Advanced
4. Disk image location
5. Pfad ändern, z. B.:D:\Docker\wsl
6. Apply & Restart

➡️ Docker:

• shuts down WSL
• moves the VHDX
• re-mounts it

✅ No data loss
✅ No export/import
✅ Clean & update-proof

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