Error: El datanode no se levanta

Al utilizar el comando jps no aparecía el datanode, revisando este log:

tail -n 20 /usr/local/hadoop/logs/hadoop-hadoop-datanode-hadoop-VirtualBox.log

 Me aparecia el siguiente error

STARTUP_MSG:   build = https://svn.apache.org/repos/asf/hadoop/common -r 1529768; compiled by 'hortonmu' on 2013-10-07T06:28Z

STARTUP_MSG:   java = 1.7.0_55

************************************************************/

2014-08-24 19:26:09,907 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: registered UNIX signal handlers for [TERM, HUP, INT]

2014-08-24 19:26:14,307 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Invalid dfs.datanode.data.dir /home/hadoop/mydata/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:158)

 at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:635)

 at org.apache.hadoop.fs.FilterFileSystem.setPermission(FilterFileSystem.java:468)

 at org.apache.hadoop.util.DiskChecker.mkdirsWithExistsAndPermissionCheck(DiskChecker.java:130)

 at org.apache.hadoop.util.DiskChecker.checkDir(DiskChecker.java:146)

 at org.apache.hadoop.hdfs.server.datanode.DataNode$DataNodeDiskChecker.checkDir(DataNode.java:1698)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.getDataDirsFromURIs(DataNode.java:1745)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1722)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1642)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1665)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:1837)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:1858)

2014-08-24 19:26:14,366 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Exception in secureMain

java.io.IOException: All directories in dfs.datanode.data.dir are invalid: "/home/hadoop/mydata/hdfs/datanode" 

 at org.apache.hadoop.hdfs.server.datanode.DataNode.getDataDirsFromURIs(DataNode.java:1754)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1722)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1642)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1665)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:1837)

 at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:1858)

2014-08-24 19:26:14,403 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1

2014-08-24 19:26:14,489 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG: 

Solucione el problema con este post, basicamente:

1.) Parar el cluster: stop-all.sh
2.) Cambiar permisos de la carpeta donde apunta la variable dfs.datanode.data.dir (especificado en hdfs-site.xml)
sudo chown hduser:hadoop -R /home/hadoop/mydata/hdfs/
sudo chmod 777 -R
3.) Formatear el namenode y arrancar de nuevo
hadoop namenode -format
start-all.sh