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

As mentioned in issue #18867 - Delete data in a container devicemapper can not free used space from Github.com

Try running the below command:

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

It uses the fstrim tool to trim the devicemapper thinly-provisioned disk.