Description of hadoop Default Configuration

5. Check the error

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1. Permission issues:

At startup, you may see a series of errors without access permissions.

Open hadoop-env.sh

Note the following:

Must have the read permission:Hadoop_conf_dir

You must have the write permission:Hadoop_log_dir, hadoop_secure_dn_log_dir, hadoop_pid_dir, hadoop_secure_dn_pid_dir

Hadoop_conf_dirIf you do not have the read permission, you cannot read the configuration file.

Hadoop_log_dir, hadoop_secure_dn_log_dir, hadoop_pid_dir, hadoop_secure_dn_pid_dirIf you do not have the write permission, logs and important data cannot be written.

2. No permission, but it seems that it has not started

In most cases, the configuration file is not found.

Hadoop_conf_dirIs where the hadoop configuration file is stored. If you do not have additional settings

Export hadoop_conf_dir =$ {hadoop_conf_dir :-"/Etc/hadoop"} The bold part is the default configuration directory.XML must be stored in this directoryOtherwise, hadoop cannot be found and the daemon cannot be started!

Description of hadoop Default Configuration