I have only one configuration file for the logging system. I have commented all categories out, but the root one.
<appender name="LSDailyRolling" class="com.lightstreamer.log4j.RelativeFileAppenders$DailyRollingFileAppender">
<param name="File" value="../logs/server.log" />
<!-- <param name="Threshold" value="INFO" /> -->
<param name="DatePattern" value="'.'yyyy-MM-dd" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d %-5p [%c] %m%n"/>
</layout>
</appender>
...
<root>
<level value="INFO"></level>
<appender-ref ref="LSDailyRolling"/>
<appender-ref ref="LSConsole"/>
</root>