log4net - Keep NHibernate out of my app's log files and into it's own file

Question

I have successfully cordoned off my own logging into its own General & Error Log files.

I have added NHibernate to the mix as i'd like to record the sql statements it generates to aid debugging - but into its own file.

With the current config I have below, the NH output is ending up in my General Log file (CommunicationsAppender) as well as it's own file (it is duplicated). How do I keep the output out of CommunicationsAppender?

<log4net> 
    <appender name="NHibernateAppender" type="log4net.Appender.RollingFileAppender">
        <file value="c:\logs\NHibernate.log"/>
        <appendToFile value="true"/>
        <maximumFileSize value="1000KB"/>
        <maxSizeRollBackups value="10"/>
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date %logger %level - %message%newline"/>
        </layout>
        <filter type="log4net.Filter.LevelRangeFilter">
            <levelMin value="DEBUG" />
            <levelMax value="FATAL" />
        </filter>
        <filter type="log4net.Filter.LoggerMatchFilter">
            <loggerToMatch value="NHibernate.SQL" />
            <acceptOnMatch value="true" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
    </appender>
    <appender name="CommunicationsAppender" type="log4net.Appender.RollingFileAppender">
        <file value="C:\Logs\Communications Service.log"/>
        <appendToFile value="true"/>
        <maximumFileSize value="10000KB"/>
        <maxSizeRollBackups value="10"/>
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date %logger - %message%newline"/>
        </layout>

        <filter type="log4net.Filter.LevelRangeFilter">
            <levelMin value="DEBUG" />
            <levelMax value="WARN" />
        </filter>
        <filter type="log4net.Filter.LoggerMatchFilter">
            <loggerToMatch value="CommunicationsLogger" />
            <acceptOnMatch value="true" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
    </appender>
    <appender name="CommunicationsErrorAppender" type="log4net.Appender.RollingFileAppender">
        <file value="C:\Logs\Communications Service Errors.log"/>
        <appendToFile value="true"/>
        <maximumFileSize value="10000KB"/>
        <maxSizeRollBackups value="10"/>
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date %logger - %message%newline"/>
        </layout>
        <filter type="log4net.Filter.LevelRangeFilter">
            <levelMin value="ERROR" />
            <levelMax value="FATAL" />
        </filter>
        <filter type="log4net.Filter.LoggerMatchFilter">
            <loggerToMatch value="CommunicationsLogger" />
            <acceptOnMatch value="true" />
        </filter>
    </appender>

    <root>
        <!-- Value of priority may be ALL, DEBUG, INFO, WARN, ERROR, FATAL, OFF -->
        <priority value="ALL"/>
        <!--<appender-ref ref="LogToFile"/>-->
        <appender-ref ref="CommunicationsAppender" />
        <appender-ref ref="CommunicationsErrorAppender" />
        <appender-ref ref="NHibernateAppender" />
    </root>
    <logger name="NHibernate.SQL">
        <level value="DEBUG"/>
        <appender-ref ref="NHibernateAppender"/>
    </logger>
    <logger name="NHibernate">
        <level value="OFF" />
    </logger>
</log4net>

Answer 1

Remove the NHibernate appender from your root and also add additivity="false" to your nhibernate appender.

<root>
    <!-- Value of priority may be ALL, DEBUG, INFO, WARN, ERROR, FATAL, OFF -->
    <priority value="ALL"/>
    <!--<appender-ref ref="LogToFile"/>-->
    <appender-ref ref="CommunicationsAppender" />
    <appender-ref ref="CommunicationsErrorAppender" />
</root>

<logger name="NHibernate.SQL" additivity="false">