在配置innodb_data_file_path=ibdata1:200M:autoextend時，想增加空間，默認文件不斷增加直到200M,如果要增加大小，直接修改參數增加大小會報錯：
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!
這里解決辦法是：
innodb_data_file_path = ibdata1:200M;ibdata2:500M:autoextend
增加一個ibdata2文件，文件大小可以設置大些，原來的文件大小保持不變，然后重啟成功。記住，這里只有最后一個文件可以autoextend。