hadoop常见问题解决

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我的CSDN博客地址： http://blog.csdn.net/qidong7

常见问题解决：
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WARN mapred.LocalJobRunner: job_local910166057_0001
org.apache.hadoop.security.AccessControlException: org.apache.hadoop.security.AccessControlException: Permission denied: user=***, access=WRITE, inode="wordcount":root:supergroup:rwxr-xr-x


sulution：added this entry to conf/hdfs-site.xml


dfs.permissions
false


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ERROR org.apache.hadoop.hdfs.server.namenode.SafeModeException:  
Cannot create /mapreduce/wordcount/output/1. Name node is in  
safe mode. 

代码中添加
conf.set("dfs.permissions","false");

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ERROR security.UserGroupInformation: PriviledgedActionException as:bc_qi cause:org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory /mapreduce/wordcount/output/1 already exists

执行
hadoop fs -rmr /mapreduce/wordcount/output

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提示连不上 50010 端口；
查看是不是防火墙的原因。
照样子添加 /etc/sysconfig/iptables 端口过滤

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