Why is docker image eating up my disk space that is not used by docker

Question

I have setup docker and I have used completely different block device to store docker\'s system data:

[root@blink1 /]# cat /etc/sysconfig/docker
# /etc/sysc         


        

Answer 1

I had a similar problem and I think this happens when you don't have enough space in the disk for all your docker images. I had 6GB reserved for docker images which it turned out not to be enough in my case. Anyway, I had removed every image and container and still disk looked full. Most of the space was being used by /var/lib/docker/devicemapper and /var/lib/docker/tmp.

This command didn't work for me:

# docker ps -qa | xargs docker inspect --format='{{ .State.Pid }}' | xargs -IZ fstrim /proc/Z/root/

First, I stopped docker service:

sudo service docker stop

Then I deleted /var/lib/docker:

Then I did what somebody suggested here in https://github.com/docker/docker/issues/18867#issuecomment-232301073

• Remove existing instance of docker metadata rm -rf /var/lib/docker

  sudo rm -rf /var/lib/docker

• Pass following options to docker daemon: -s devicemapper --storage-opt dm.fs=xfs --storage-opt dm.mountopt=discard

• Start docker daemon.

For last two steps, I run:

sudo dockerd -s devicemapper --storage-opt dm.fs=xfs --storage-opt dm.mountopt=discard