/var/lib/mysqlshow variables like "%datadir%";
systemctl stop mariadb
mv /var/lib/mysql/ /home/
vim /etc/my.cnf.d/server.cnf
datadir=/home/mysql
vim /usr/lib/systemd/system/mariadb.service
#防止写入/usr、/boot和/etc
ProtectSystem=false
#防止访问/home、/root和/run/user
ProtectHome=false

systemctl daemon-reload
systemctl start mariadb.service
chown -R mysql:mysql /home/mysql/