When i try to start the hadoop on master node i am getting the following output.and the namenode is not starting.
[hduser@dellnode1 ~]$ start-dfs.sh
starting namenode, logging to /usr/local/hadoop/bin/../logs/hadoop-hduser-namenode-dellnode1.library.out
dellnode1.library: datanode running as process 5123. Stop it first.
dellnode3.library: datanode running as process 4072. Stop it first.
dellnode2.library: datanode running as process 4670. Stop it first.
dellnode1.library: secondarynamenode running as process 5234. Stop it first.
[hduser@dellnode1 ~]$ jps
5696 Jps
5123 DataNode
5234 SecondaryNameNode
When a NameNode starts up, it merges the fsimage and edits journal to provide an up-to-date view of the file system metadata. The NameNode then overwrites fsimage with the new HDFS state and begins a new edits journal. The Checkpoint node periodically creates checkpoints of the namespace.
You can stop the NameNode individually using /sbin/hadoop-daemon.sh stop namenode command. Then start the NameNode using /sbin/hadoop-daemon.sh start namenode. Use /sbin/stop-all.sh and the use /sbin/start-all.sh, command which will stop all the demons first. Then start all the daemons.
If NameNode fails, the entire Hadoop cluster will fail. Actually, there will be no data loss, only the cluster job will be shut down because NameNode is just the point of contact for all DataNodes and if the NameNode fails then all communication will stop.
According to running "stop-all.sh" on newer versions of hardoop, this is deprecated. You should instead use:
stop-dfs.sh
and
stop-yarn.sh
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