@Aruna Sameera The "hadoop namenode -format" command formats the specified NameNode. It starts the NameNode, formats it and then shut it down. dfs.namenode.name.dir: Determines where on the local filesystem the DFS name node should store the name table(fsimage). If this is a comma-delimited list of directories then the name table is replicated in all of the directories, for redundancy. with default value ${hadoop.tmp.dir}/dfs/name. dfs.datanode.data.dir: (default: file://${hadoop.tmp.dir}/dfs/data) - Determines where on the local filesystem an DFS data node should store its blocks. hadoop.tmp.dir: "/tmp/hadoop-${user.name}" (Default) - A base for other temporary directories. . Please check the values of above parameters defined in your core-site.xml/hdfs-site.xml . Ref: https://hadoop.apache.org/docs/r2.7.3/hadoop-project-dist/hadoop-common/core-default.xml The Default values are determined as mentioned in the link: https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml#L332-L339 <property> <name>dfs.namenode.name.dir</name> <value>file://${hadoop.tmp.dir}/dfs/name</value> <description>Determines where on the local filesystem the DFS name node should store the name table(fsimage). If this is a comma-delimited list of directories then the name table is replicated in all of the directories, for redundancy. </description> </property> . ... View more

@Aruna Sameera First you will have to generate the "ssh-keys" Example: (Use all default values ... keep pressing enter with the "ssh-key" command.) I mean empty passphrase. $ ssh-keygen Generating public/private rsa key pair. Enter file in which to save the key (/home/jay/.ssh/id_rsa): Created directory '/home/jay/.ssh'. Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/jay/.ssh/id_rsa. Your public key has been saved in /home/jay/.ssh/id_rsa.pub. The key fingerprint is: a1:70:20:75:52:aa:c6:0c:66:1e:c5:e6:61:11:91:43 jay@erie1.example.com The key's randomart image is: +--[ RSA 2048]----+ | ..o ...+E+ | | . o=.o = | | .+.A.o o | | o..*.o | | . Ao | | | | | | | | | +-----------------+ The easiest approach will be to use the "ssh-copy-id" command: Example: ssh-copy-id -i ~/.ssh/id_rsa.pub localhost ssh-copy-id -i ~/.ssh/id_rsa.pub kerbambari1.example.com ssh-copy-id -i ~/.ssh/id_rsa.pub kerbambari2.example.com ssh-copy-id -i ~/.ssh/id_rsa.pub kerbambari3.example.com ssh-copy-id -i ~/.ssh/id_rsa.pub kerbambari4.example.com . ... View more

@Aruna Sameera port below to 1024 are reserved ports. Can you check if the port 22 is open? And if user "aruna" has permission to open it? I ssh service is running on port 22 ? Also please check if the "openssh-server" is installed or not? If not then please install it as mentioned in: http://linux-sys-adm.com/how-to-install-and-configure-ssh-on-ubuntu-server-14.04-lts-step-by-step/ . ... View more