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From Harsh J <ha...@cloudera.com>
Subject Re: Error on running map reduce job
Date Wed, 01 Feb 2012 11:41:27 GMT
Sesha,

Per http://bit.ly/yUWDh4, it helps if your mapred.system.dir is owned
by the user running JobTracker (mostly 'mapred' if you use packages).
Can you verify if thats the case on your cluster as well? Does user
'master' run the JobTracker?

On Tue, Jan 31, 2012 at 1:18 PM, Sesha Kumar <sesha911@gmail.com> wrote:
> Hi guys,
>                I'm having a problem running map reduce jobs in
> hadoop. Whenever I try to run a map reduce job, I get the following
> exception:
>
> Caused by: org.apache.hadoop.ipc.RemoteException:
> org.apache.hadoop.security.AccessControlException: Permission denied:
> user=slave, access=EXECUTE,
> inode="map_red":master:supergroup:rwx------
>        at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:199)
>        at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkTraverse(FSPermissionChecker.java:155)
>        at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:125)
>        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4811)
>        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkTraverse(FSNamesystem.java:4790)
>        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getFileInfo(FSNamesystem.java:1876)
>        at org.apache.hadoop.hdfs.server.namenode.NameNode.getFileInfo(NameNode.java:747)
>
> Note: this is not the entire stack trace.
>
> I found that this occurred because of the directory "/map_red" inside
> HDFS does not have necessary permissions.
>
> I use the command "hadoop fs -chmod -R" to change the permissions of
> /map_red to 777 after which the map reduce job works properly.
>
> Next time a map reduce job runs, the permissions are reverted back to
> rwx------, i need to do the same thing again to get it working.
>
> Is there any way to ensure that the permissions of /map_red always
> remain as rwxrwxrwx?
>
> I've included the necessary contents of mapred-site.xml are this:
>
> ...
> ...
>   <property>
>        <name>mapred.temp.dir</name>
>        <value>/map_red_temp</value>
>    </property>
>    <property>
>        <name>mapred.system.dir</name>
>        <value>/map_red</value>
>    </property>
> ...
> ...



-- 
Harsh J
Customer Ops. Engineer
Cloudera | http://tiny.cloudera.com/about

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