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This article mainly introduces how to solve the no namenode to stop exception when restarting the Hadoop cluster, which has certain reference value. Interested friends can refer to it. I hope you will learn a lot after reading this article. Let's take a look at it.

The configuration file of the hadoop cluster has been modified and the cluster needs to be restarted, but the error is as follows:

[hadoop@master ~] # stop-dfs.shStopping namenodes on [master] master1: no namenode to stopmaster2: no namenode to stopslave2: no datanode to stopslave1: no datanode to stop

The cause of the problem is that hadoop is based on journalnode on datanode and pid on dfs when stop. The default process number is saved under / tmp, and linux deletes files in this directory by default (usually a month or 7 days or so).

So after deleting the hadoop-hadoop-journalnode.pid and hadoop-hadoop-datanode.pid files, namenode naturally can't find the two processes on datanode.

Configuring export HADOOP_PID_DIR in the configuration file hadoop_env.sh can solve this problem, or you can modify it in hadoop-deamon.sh, which calls hadoop_env.sh. Change the path of HADOOP_PID_DIR to "/ var/hadoop_pid". Remember to manually create a hadoop_pid folder in the "/ var" directory and assign owner permissions to the hadoop user.

[hadoop@slave3 ~] $ls / var/hadoop_pid/hadoop-hadoop-datanode.pid hadoop-hadoop-journalnode.pid

Then manually kill the Datanode process (kill-9 pid) on the faulty Slave, rerun start-dfs..sh and find that there is no "no datanode to stop" and "no namenode to stop", and the problem is solved.

[hadoop@master1 ~] $start-dfs.sh16/04/13 17:20:26 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... Using builtin-java classes where applicableStarting namenodes on [master1 master2] master1: starting namenode, logging to / data/usr/hadoop/logs/hadoop-hadoop-namenode-master1.outmaster2: starting namenode, logging to / data/usr/hadoop/logs/hadoop-hadoop-namenode-master2.outslave4: starting datanode, logging to / data/usr/hadoop/logs/hadoop-hadoop-datanode-slave4.outslave3: starting datanode, logging to / data/usr/hadoop/logs/hadoop-hadoop-datanode-slave3.outslave2: starting datanode Logging to / data/usr/hadoop/logs/hadoop-hadoop-datanode-slave2.outslave1: starting datanode, logging to / data/usr/hadoop/logs/hadoop-hadoop-datanode-slave1.outStarting journal nodes [master1 master2 slave1 slave2 slave3] slave3: starting journalnode, logging to / data/usr/hadoop/logs/hadoop-hadoop-journalnode-slave3.outmaster1: starting journalnode, logging to / data/usr/hadoop/logs/hadoop-hadoop-journalnode-master1.outslave1: starting journalnode, logging to / data/usr/hadoop/logs/hadoop-hadoop-journalnode-slave1.outmaster2: starting journalnode Logging to / data/usr/hadoop/logs/hadoop-hadoop-journalnode-master2.outslave2: starting journalnode, logging to / data/usr/hadoop/logs/hadoop-hadoop-journalnode-slave2.out16/04/13 17:20:40 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... Using builtin-java classes where applicableStarting ZK Failover Controllers on NN hosts [master1 master2] master1: starting zkfc, logging to / data/usr/hadoop/logs/hadoop-hadoop-zkfc-master1.outmaster2: starting zkfc, logging to / data/usr/hadoop/logs/hadoop-hadoop-zkfc-master2.out Thank you for reading this article carefully. I hope the article "how to solve the no namenode to stop exception when restarting the Hadoop cluster" shared by the editor will be helpful to you. At the same time, I hope you will support it. Pay attention to the industry information channel, more related knowledge is waiting for you to learn!

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