执行

mysqld --initialize-insecure --user=mysql --datadir=/data/3309/data --basedir=/usr
mysqld: Can't create directory '/data/3308/data/' (Errcode: 13 - Permission denied)
mysqld: Can't create directory '/data/3308/data/' (Errcode: 17 - File exists)
1.查看日志
journalctl -xe
终端输出结果:
apparmor="DENIED"  operation="mkdir" profile="/usr/sbin/mysqld"  name="/data/3307/data/" pid=27174 comm="mysqld"  requested_mask="c" denied_mask="c" fsuid=0 ouid=0
其他相关错误
apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/data/3307/my.cnf" pid=29707 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=108 ouid=108
说明: apparmor 授权失败.
#文件路径 /etc/apparmor.d/usr.sbin.mysqld
vim /etc/apparmor.d/usr.sbin.mysqld
# 默认配置
# Allow data dir access
  /var/lib/mysql/ r,
  /var/lib/mysql/** rwk,
# 添加如下
#'r' (read), 'w' (write), 'm' (memory map as executable), 'k' (file locking), and 'l' (creation hard links)
  /data/3308/data/ rw,
  /data/3308/data/** rwk,
3.重启apparmor
service apparmor restart
4.如果出现 [ERROR] Can't change data directory owner to mysql