Namenode not getting started

Question

I was using Hadoop in a pseudo-distributed mode and everything was working fine. But then I had to restart my computer because of some reason. And now when I am trying to st

Answer 1

Open a new terminal and start the namenode using path-to-your-hadoop-install/bin/hadoop namenode

The check using jps and namenode should be running

Answer 2

For me the following worked after I changed the directory of the namenode and datanode in hdfs-site.xml

-- before executing the following steps stop all services with stop-all.sh or in my case I used the stop-dfs.sh to stop the dfs

1. On the new configured directory, for every node (namenode and datanode), delete every folder/files inside it (in my case a 'current' directory).
2. delete the Hadoop temporary directory: $rm -rf /tmp/haddop-$USER
3. format the Namenode: hadoop/bin/hdfs namenode -format
4. start-dfs.sh

After I followed those steps my namenode and datanodes were alive using the new configured directory.

Answer 3

In core-site.xml:

    <configuration>
       <property>
          <name>fs.defaultFS</name>
          <value>hdfs://localhost:9000</value>
       </property>
       <property>
          <name>hadoop.tmp.dir</name>
          <value>/home/yourusername/hadoop/tmp/hadoop-${user.name}
         </value>
  </property>
</configuration>

and format of namenode with :

hdfs namenode -format

worked for hadoop 2.8.1

Answer 4

I ran into the same thing after a restart.

for hadoop-2.7.3 all I had to do was format the namenode:

<HadoopRootDir>/bin/hdfs namenode -format

Then a jps command shows

6097 DataNode
755 RemoteMavenServer
5925 NameNode
6293 SecondaryNameNode
6361 Jps

Answer 5

If your namenode is stuck in safemode you can ssh to namenode, su hdfs user and run the following command to turn off safemode:

hdfs dfsadmin -fs hdfs://server.com:8020 -safemode leave

Answer 6

Following STEPS worked for me with hadoop 2.2.0,

STEP 1 stop hadoop

hduser@prayagupd$ /usr/local/hadoop-2.2.0/sbin/stop-dfs.sh

STEP 2 remove tmp folder

hduser@prayagupd$ sudo rm -rf /app/hadoop/tmp/

STEP 3 create /app/hadoop/tmp/

hduser@prayagupd$ sudo mkdir -p /app/hadoop/tmp
hduser@prayagupd$ sudo chown hduser:hadoop /app/hadoop/tmp
hduser@prayagupd$ sudo chmod 750 /app/hadoop/tmp

STEP 4 format namenode

hduser@prayagupd$ hdfs namenode -format

STEP 5 start dfs

hduser@prayagupd$ /usr/local/hadoop-2.2.0/sbin/start-dfs.sh

STEP 6 check jps

hduser@prayagupd$ $ jps
11342 Jps
10804 DataNode
11110 SecondaryNameNode
10558 NameNode