MySQL modified innodb_log_file_size parameter causes INNODB engine to be invalid

Today, when MySQL was optimized, the following error occurred after restarting MySQL:

Innodb_buffer_pool_size=768m
innodb_log_file_size=256m
innodb_log_buffer_size=8m
innodb_additional_mem_pool_size=4m
Innodb_flush_log_at_trx_commit=0
Innodb_thread_concurrency=20

The above is an initial optimization of the InnoDB engine, we are replacing all parameters at once, then saving the configuration file and then unable to start Mysql,manager of Pid-file quit with[failed]dating file

The last step is to find the update innodb_log_file_size=256m when there is a problem, as long as the addition of this can not start

The reason for this error is that I set the Default-storage-engine=innodb in the accessories file to set the database default engine to InnoDB, if the default engine is modified to MyISAM, it will not error, but the InnoDB engine is invalid.

I then eliminated the changed configuration file, and finally found it on the innodb_log_file_size parameter. Later looked at the data, found that the modification of this parameter will need to stop MySQL,

Then delete the Ib_logfile0...ib_logfilen file under the $mysql_home/var directory, and then start MYSQL.