Issue1: Create more free space in thin pool or use dm.min_free_space option to change behavior

问题：在docker pull的时候遇到如下问题

failed to register layer: devmapper: Thin Pool has 107394 free data blocks which is less than minimum required 163840 free data blocks. Create more free space in thin pool or use dm.min_free_space option to change behavior

解决方法：

http://stackoverflow.com/questions/36918387/space-issue-on-docker-devmapper-and-centos7

1. Cleanup exited processes:

   docker rm $(docker ps -q -f status=exited)
   

2. Cleanup dangling volumes:

   docker volume rm $(docker volume ls -qf dangling=true)
   

3. Cleanup dangling images:

   docker rmi $(docker images --filter "dangling=true" -q --no-trunc)

4. 再次pull镜像，正常了
5.