Running Docker on a system with limited internal storage can quickly become a problem. Docker stores images, volumes, and its virtual disk in a single data directory, which can grow rapidly and trigger the familiar “Your disk is almost full” warning.

This guide shows you how to relocate Docker’s data to an external drive, allowing you to reclaim valuable internal storage while keeping Docker reliable and performant.

Prerequisites:

Docker Desktop installed in your system
An external SSD drive preferably with 1TB

Step 1: Locating the docker data directory and the disk image

At the time of writing this tutorial, I was using Docker Desktop version 4.55, and the data directory was located at:

~/Library/Containers/com.docker.docker/Data/vms/0/data

Within this directory, you should find a file named Docker.raw, which is used to store all Linux containers, images, and volumes inside a virtual machine (VM).

Step 2: Stop Docker Desktop

For this we can simply use Quite Docker Desktop option from the UI menu, or use commands below

killall Docker
killall com.docker.backend

Alternatively, you can also use the Activity Monitor in Mac to terminate the Docker processes.

Step 3: Copying the Docker.raw to the external device

Create a directory on your external storage device with a name of your choice (in my case, DockerData). Then copy the Docker.raw file into this directory, either by using copy and paste or by running the command below.

mv ~/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw \
   "/Volumes/YourExternalDrive/DockerData/Docker.raw"

This may take a few minutes to copy to the external drive, as the Docker.raw file can be quite large. In my case, it was around 245GB.

Step 4: Creating a symlink

The next step is to create a symlink. Before doing so, make sure to rename the existing Docker.raw file in the local directory (i.e. ~/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw) for backup purposes, something like Docker_backup.raw.

Then perform the symlink as below.

ln -s "/Volumes/YourExternalDrive/DockerData/Docker.raw" \
      ~/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw

The above will result in creating symlink file within ~/Library/Containers/com.docker.docker/Data/vms/0/data/)

Use the command below to verify that the symlink was created successfully.

ls -ld ~/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw

This should output something like below

 /Users/User/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw -> /Volumes/YourExternalDrive/DockerData/Docker.raw

Step 5: Testing Docker

Open Docker Desktop and ensure it loads successfully without any errors. Then run the command below to confirm that the images are pulled and running correctly.

docker run hello-world

Step 6: Clean up

If everything is working as expected, you can safely remove the backup file you renamed in Step 4 from the local directory.

Gear Used

Crucial X9 with 1TB capacity as an APFS volume