Resize disk usage of a Docker container

Question

Every Docker container will be configured with 10 GB disk space, which is the default configuration of devicemapper in CentOS. So how can I configure every container newly created with more than 10 GB disk space in default? (The host server is installed with CentOS 6 and Docker 1.7.1)

Answer 1

1. (optional) If you have already downloaded any image via docker pull you need to clean them first - otherwise they won't be resized

   docker rmi your_image_name

2. Edit the storage config

   vi /etc/sysconfig/docker-storage

   There should be something like DOCKER_STORAGE_OPTIONS="...", change it to DOCKER_STORAGE_OPTIONS="... --storage-opt dm.basesize=100G"

3. Restart the docker deamon

   service docker restart

4. Pull the image

   docker pull your_image_name

5. (optional) verification

   docker run -i -t your_image_name /bin/bash

   df -h

I was struggling with this a lot until I found out this link http://www.projectatomic.io/blog/2016/03/daemon_option_basedevicesize/ turns out you have to remove/pull image after enlarging the basesize.

Answer 2

Yes you can. Use the dm.basesize attribute when starting the Docker daemon. For example:

docker daemon --storage-opt dm.basesize=50G ...

More info can be found in the official docs.