问题1：在DFS Lcation 上不能多文件进行操作：

在Hadoop上的每个节点上修改该文件       conf/mapred-site.xml

         增加： 

                   <property>

                   <name>dfs.permissions</name>

                   <value>false</value>

                   </property>

         关闭权限验证

问题2

log4j:WARN No appenders could be foundfor logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).

log4j:WARN Please initialize the log4jsystem properly.

log4j:WARN Seehttp://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

在src文件夹下创建以log4j.properties命名的文件

文件内容如下log4j.rootLogger=debug,stdout,R
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p - %m%n
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=mapreduce_test.log
log4j.appender.R.MaxFileSize=1MB
log4j.appender.R.MaxBackupIndex=1
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
log4j.logger.com.codefutures=DEBUG

Hadoop-2.7.3 问题收集