Different log appenders for the different app server instances, the logger name in the configuration "ServerA" and "ServerB" are the app servers' names in your SuperSocket configuration

log4net.xml

<?xml version="1.0" encoding="utf-8" ?>
<log4net>
    <appender name="errorAppender" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="ERROR" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\err.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="infoAppender" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="INFO" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\info.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="debugAppender" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="DEBUG" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\debug.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
  <appender name="errorAppenderA" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="ERROR" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\ServerA\err.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="infoAppenderA" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="INFO" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\ServerA\info.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="debugAppenderA" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="DEBUG" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\ServerA\debug.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
	<appender name="infoAppenderB" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="INFO" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\ServerB\info.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="debugAppenderB" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="DEBUG" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\ServerB\debug.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>
    <appender name="perfAppender" type="log4net.Appender.RollingFileAppender">
        <filter type="log4net.Filter.LevelMatchFilter">
            <levelToMatch value="INFO" />
        </filter>
        <filter type="log4net.Filter.DenyAllFilter" />
        <File value="Logs\perf.log" />
        <PreserveLogFileNameExtension value="true" />
        <appendToFile value="true" />
        <rollingStyle value="Date" />
        <datePattern value="yyyyMMdd" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date %logger - %message%newline" />
        </layout>
    </appender>
    <root>
        <level value="ALL" />
        <appender-ref ref="errorAppender" />
        <appender-ref ref="infoAppender" />
        <appender-ref ref="debugAppender" />
    </root>
    <logger name="Performance" additivity="false">
      <level value="ALL" />
      <appender-ref ref="perfAppender" />
    </logger>
    <logger name="ServerA" additivity="false">
      <level value="ALL" />
      <appender-ref ref="errorAppenderA" />
      <appender-ref ref="infoAppenderA" />
      <appender-ref ref="debugAppenderA" />
    </logger>
    <logger name="ServerB" additivity="false">
      <level value="ALL" />
      <appender-ref ref="errorAppenderB" />
      <appender-ref ref="infoAppenderB" />
      <appender-ref ref="debugAppenderB" />
    </logger>
</log4net>