I finally solved this for my setup today and wanted to share what worked.
I had a situation where I had orphaned volumes.
I figured it out by using commands from earlier in this thread.
I ran this command from earlier in the thread from beastieg on 2/4/2021
docker ps | awk '{print $1}' | grep -v CONTAINER | xargs -n 1 -I {} sh -c "echo -e \\\n#================\\\nDocker container:{}; docker exec {} du -hx -d1 / "
It showed that none of my active containers were using much space.
I then found this stackoverflow post on deleting orphaned volumes
https://stackoverflow.com/questions/27812807/orphaned-docker-mounted-host-volumes
I ran this command that showed I had 3 orphaned volumes:
docker volume ls -qf dangling=true
I then ran this one to delete them:
docker volume rm $(docker volume ls -qf dangling=true)
I hope if you ended up here as I did after googling the high utilization message that unraid presented, that this might help you as well.
Good Luck.
