I got the same error in a weblogic server 11g running in ubuntu 10.10. I have multiple applications logging in the same file.

ERROR in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - Appender [FILE] failed to append. java.nio.channels.OverlappingFileLockException
        at java.nio.channels.OverlappingFileLockException
        at at sun.nio.ch.FileChannelImpl$SharedFileLockTable.checkList(FileChannelImpl.java:1166)
        at at sun.nio.ch.FileChannelImpl$SharedFileLockTable.add(FileChannelImpl.java:1068)
        at at sun.nio.ch.FileChannelImpl.lock(FileChannelImpl.java:824)
        at at java.nio.channels.FileChannel.lock(FileChannel.java:860)
        at at ch.qos.logback.core.FileAppender.safeWrite(FileAppender.java:187)
        at at ch.qos.logback.core.FileAppender.writeOut(FileAppender.java:204)
        at at ch.qos.logback.core.OutputStreamAppender.subAppend(OutputStreamAppender.java:212)
        at at ch.qos.logback.core.rolling.RollingFileAppender.subAppend(RollingFileAppender.java:148)
        at at ch.qos.logback.core.OutputStreamAppender.append(OutputStreamAppender.java:103)
        at at ch.qos.logback.core.UnsynchronizedAppenderBase.doAppend(UnsynchronizedAppenderBase.java:88)
        at at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:48)
        at at ch.qos.logback.classic.Logger.appendLoopOnAppenders(Logger.java:282)
        at at ch.qos.logback.classic.Logger.callAppenders(Logger.java:269)
        at at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:470)
        at at ch.qos.logback.classic.Logger.filterAndLog_0_Or3Plus(Logger.java:424)
        at at ch.qos.logback.classic.Logger.log(Logger.java:824)


Logback configguration

<?xml version="1.0" encoding="UTF-8"?>
<configuration scan="true" debug="true">

  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <prudent>true</prudent>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <fileNamePattern>/root/log/client.log.%d{yyyy-MM-dd}</fileNamePattern>
    </rollingPolicy>

    <encoder>
      <pattern>%d [%t] %-5p [%c{0}:%L] [%X] %m%n</pattern>
    </encoder>
  </appender>

  <root level="ERROR">
    <appender-ref ref="FILE" />
  </root>
</configuration>