CentOS 6.9:MySQL Daemon failed to start.

[root@Server_1 12:02:58 ~ 25]#service mysqld start
MySQL Daemon failed to start.
Starting mysqld:

[root@Server_1 12:05:40 ~ 27]#less /var/log/mysqld.log

2018-04-18 12:04:32 5406 [ERROR] InnoDB: auto-extending data file ./ibdata1 is of a
different size 640 pages (rounded down to MB) than specified in the .cnf file: ini
tial 768 pages, max 0 (relevant if non-zero) pages!
2018-04-18 12:04:32 5406 [ERROR] InnoDB: Could not open or create the system tables
pace. If you tried to add new data files to the system tablespace, and it failed he
re, you should now edit innodb_data_file_path in my.cnf back to what it was, and re
move the new ibdata files InnoDB created in this failed attempt. InnoDB only wrote
those files full of zeros, but did not yet use them in any way. But be careful: do
not remove old data files which contain your precious data!
2018-04-18 12:04:32 5406 [ERROR] Plugin 'InnoDB' init function returned error.
2018-04-18 12:04:32 5406 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE f
ailed.
2018-04-18 12:04:32 5406 [ERROR] Unknown/unsupported storage engine: InnoDB
2018-04-18 12:04:32 5406 [ERROR] Aborting

使用的是mysql-community.repo安装的，什么都没有改，只是把5.6启用了，然后执行yum install -y mysql-community-server安装，安装完成之后启动就跑出来这个错误。