JPS has no namenode and datanode reasons

 

a key ： All the reasons can be found in hadoop Under the logs Under the table of contents namenode Find the problem in the log file of , Problems in operation will be saved to these files  

 

  Here are some main problems

reason 1

There is a problem with the configuration file

Check all hadoop The configuration file , See if there is something missing or wrong

reason 2（ It's probably this problem ）

There is a problem with the path of the node on the local machine ： The log file indicates that you cannot access namenode The path of

If you use ordinary users , Where your node is stored locally, ordinary users must have permission , Otherwise, the initialized data cannot be stored in the specified location

reason 3

You have formatted the master node many times before , But did not delete , Multiple formatting namenode It's caused namenode and datanode Of clusterID atypism , It doesn't know which one to load .

resolvent

Delete hadoop/logs All log files in the log file , And you namenode and datanode Store all file information of the path , Reformat