[root@localhost init.d]# service mysql start
Redirecting to /bin/systemctl start mysql.service
Job for mysqld.service failed because a timeout was exceeded. See "systemctl status mysqld.service" and "journalctl -xe" for details.

在日志中发现错误：
2017-12-08 14:37:52 32407 [ERROR] InnoDB: ./ibdata1 can't be opened in read-write mode
2017-12-08 14:37:52 32407 [ERROR] InnoDB: The system tablespace must be writable!
2017-12-08 14:37:52 32407 [ERROR] Plugin 'InnoDB' init function returned error.
2017-12-08 14:37:52 32407 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2017-12-08 14:37:52 32407 [ERROR] Unknown/unsupported storage engine: InnoDB
2017-12-08 14:37:52 32407 [ERROR] Aborting

2017-12-08 14:37:52 32407 [Note] Binlog end

网上找到的解决方法删除DATA文件夹下的两个文件重启mysql并不管用