What happen if innodb_log_file become full?
When innodb_log_file ib_logfile0 is full it start to write innodb_log_file ib_logfile1.

When this is full, it start to over with innodb_log_file ib_logfile0.

The only thing is to have enough space for both files.

The size is determined by `innodb_log_file_size=64M, but be careful mysql when you want to change the size, you need stop the server and delete the old ones. when you restart they will be created new.