How to migrate the data directory in Docker

# du -hs /var/lib/docker/ 
237G /var/lib/docker/

# docker system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 7 2 122.2GB 79.07GB (64%)
Containers 2 2 61.96GB 0B (0%)
Local Volumes 0 0 0B 0B
Build Cache 0 0 0B 0B

# The docker system prune command can be used to clean up disks, delete closed containers, unused data volumes and networks, and untagged images.
# The docker system prune -a command can delete all Docker images that are not used by containers. Note that these two commands will delete the temporarily closed containers and the Docker images that are not currently in use.

【Stop Docker】
# systemctl stop docker

Create a new docker directory
# mkdir -p /home/docker/lib

Migrate the /var/lib/docker directory
(Note: You can directly mv, make sure the disk is large enough)
# rsync -avz /var/lib/docker /home/docker/lib/  

【Add configuration】
Check whether /etc/systemd/system/docker.service.d/devicemapper.conf exists. If it does not exist, create it.
# mkdir -p /etc/systemd/system/docker.service.d/
# vi /etc/systemd/system/docker.service.d/devicemapper.conf
 (Note: devicemapper.conf adds configuration: when syncing, the parent folder should be synchronized together. The actual directory should be in /home/docker/lib/docker )
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd --graph=/home/docker/lib/docker

[Reload Docker] 
# systemctl daemon-reload
# systemctl restart docker
# systemctl enable docker

Check docker info
# docker info | grep "Docker Root Dir"
Is it changed to: /home/docker/lib/docker

Check the image
# docker images

【Cleaning up original data】
After confirming that the container is OK, delete the files in the /var/lib/docker/ directory.
# rm -rf /var/lib/docker