title: hadoop's datanode is not starting
body: <p>I am using ubuntu 14.04 LTS Java version 8 and Hadoop 2.5.1 for installation. I followed <a href="https://www.digitalocean.com/community/tutorials/how-to-install-hadoop-on-ubuntu-13-10" rel="noreferrer">this</a> guide  to install all the components. Sorry for not using michael noll's. 
  Now the problem that i face is when i do start-dfs.sh i get the following message <br></p>
  
  <pre><code>oroborus@Saras-Dell-System-XPS-L502X:~$ start-dfs.sh &lt;br&gt;
  14/11/12 16:12:33 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable&lt;br&gt;
  Starting namenodes on [localhost]&lt;br&gt;
  localhost: starting namenode, logging to /usr/local/hadoop/logs/hadoop-oroborus-namenode-Saras-Dell-System-XPS-L502X.out&lt;br&gt;
  localhost: starting datanode, logging to /usr/local/hadoop/logs/hadoop-oroborus-datanode-Saras-Dell-System-XPS-L502X.out&lt;br&gt;
  Starting secondary namenodes [0.0.0.0]&lt;br&gt;
  0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/logs/hadoop-oroborus-secondarynamenode-Saras-Dell-System-XPS-L502X.out&lt;br&gt;
  14/11/12 16:12:48 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable&lt;br&gt;
  </code></pre>
  
  <p>Now after running start-yarn.sh(which seems to work fine) and jps i get the following output<br></p>
  
  <pre><code>oroborus@Saras-Dell-System-XPS-L502X:~$ jps
  9090 NodeManager
  5107 JobHistoryServer
  8952 ResourceManager
  12442 Jps
  11981 NameNode
  </code></pre>
  
  <p>The ideal output should have datanode in it, but it is not there. Googling and SOing a bit i found out the error is looged in the logs so here are the logs for datanode.(Only error part if you need more let me know)<br></p>
  
  <pre><code>    2014-11-08 23:30:32,709 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: registered UNIX signal handlers for [TERM, HUP, INT]
  2014-11-08 23:30:33,132 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Invalid dfs.datanode.data.dir /usr/local/hadoop_store/hdfs/datanode :
  EPERM: Operation not permitted
          at org.apache.hadoop.io.nativeio.NativeIO$POSIX.chmodImpl(Native Method)
          at org.apache.hadoop.io.nativeio.NativeIO$POSIX.chmod(NativeIO.java:226)
          at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:642)
          at org.apache.hadoop.fs.FilterFileSystem.setPermission(FilterFileSystem.java:472)
          at org.apache.hadoop.util.DiskChecker.mkdirsWithExistsAndPermissionCheck(DiskChecker.java:126)
          at org.apache.hadoop.util.DiskChecker.checkDir(DiskChecker.java:142)
          at org.apache.hadoop.hdfs.server.datanode.DataNode$DataNodeDiskChecker.checkDir(DataNode.java:1866)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.checkStorageLocations(DataNode.java:1908)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1890)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1782)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1829)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:2005)
          at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:2029)
  2014-11-08 23:30:33,134 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Exception in secureMain
  java.io.IOException: All directories in dfs.datanode.data.dir are invalid: "/usr/local/hadoop_store/hdfs/datanode/"
          at org.apache.hadoop.hdfs.server.datanode.DataNode.checkStorageLocations(DataNode.java:1917)
  </code></pre>
  
  <p><b>Now my doubt is how to make it valid.</b>  </p>
  
  <p>Help is appreciated. <br>
  P.S. I tried a lot of forums, SO post none of them could give me solution to this problem. Hence the question.</p>