Deactivate the Generate log data option if you do not want warning and error information written to the log. However, if you do deactivate this option, the file name and time stamp are still recorded in the log.
Normally, it is recommended to leave the Generate log data option active, which is the default, as this helps you identify problems with file conversions.
Occasionally, some batch import/export create very large warning/error files, and in this case you might want to disable this option.