I found that there are a lot of mounts under /var/lib/docker/volumnes/, and none of them have been deleted. Now I delete all of them, and then stop the container, delete it, and start it again.
Adding the -v parameter when the container is deleted in the future will delete the associated volume. docker-compose rm -v
refer to:
http://blog.csdn.net/west_609/article/details/5828367 Find the problem, where the most files are
http://dockone.io/article/128
http://dockerpool.com/static/books/docker_practice/compose/yaml_file.html
http://cholerae.com/2015/04/13/-%E7%BF%BB%E8%AF%91-Docker-Compose%E5%B7%A5%E5%85%B7%E5%BF%AB%E9%80%9F%E5%85%A5%E9%97%A8/