在配置innodb_data_file_path=ibdata1:200M:autoextend时，想增加空间，默认文件不断增加直到200M,如果要增加大小，直接修改参数增加大小会报错：
auto-extending data file ./ibdata1 is of a different size 12800 pages (rounded down to MB) than specified in the .cnf file: initial 32000 pages, max 0 (relevant if non-zero) pages!
2017-11-08 12:06:48 140262644676864 [ERROR] InnoDB: Could not open or create the system tablespace. If you tried to add new data files to the system tablespace, and it failed here, you should now edit innodb_data_file_path in my.cnf back to what it was, and remove 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!
这里解决办法是：
innodb_data_file_path = ibdata1:200M;ibdata2:500M:autoextend
增加一个ibdata2文件，文件大小可以设置大些，原来的文件大小保持不变，然后重启成功。记住，这里只有最后一个文件可以autoextend。