data-root was the ideal solution for me on 18.04.
I followed your tip and finally found a great workflow/procedure to follow for my migration Change Docker Data Directory on Debian - check out the disqus comment as well, as I had a little issue, that was due to my specific installation of portainer.io - the first startup of my “moved” containers did not succeed, but stopping and starting then brought them back to life.
Yes “data-root” is the ideal solution for RHEL 7.x and Docker-EE environment as well who are using Docker engine version 17.05 or above as because “graph” option is now deprecated from engine version 17.05.
For more details please follow the below links about it.
https://github.com/moby/moby/issues/3127 and https://github.com/moby/moby/pull/28696
For me, below change in “/etc/docker/daemon.json” file perfectly worked.
thank you very much! helped me a lot!