Name node or Data node not starting

If you come across these problems :

Data node not starting :

          Solution you can try :

              1.  "chown" of hdfs folderr to the current user

              2.  " chmod" of hdfs folder to 755 to the current user

              3.  delete the hdfs folder and reformat (hadoop namenode -format) if 1 and 2 does not work

     Note : Problem with data node generally occurs due to file permission.

Name node not starting

          Solution you can try:

               1. Comment out or remove the entry 127.0.1.1

               2. Check your ip/dns setting, name node problem generally related to domain/IP

              3. Also check if you name/IP you are specifying in the hadoop setting xml can be resolved. you can do this bye pinging/ or telnetting the IP/Domain you have specified for the hadoop settings.

     Note : Problem related to name node generally occurs due to domain/IP related problems.

     

Data node is not starting for hadoop

Check for the folder permission and folder ownership, for HDFSand Hadoop folder,

So change the ownership of the hadoop or hdfs folder you can issue the following command at the shell

chown -R username foldername

Here -R says recursive, so the foldername and the folder under it will be affected and the folder name will be either your Hadoop folder or HDFSfolder if it is created successfully, the you can look into changing the permission of the folder which you can do by issuing the following command at shell

chmod -R 755 foldername

And also you can check if data folder is created sucessfully in hdfs path that you have specified.


Note :