What are the common mistakes in hadoop
This article mainly introduces what are the common mistakes in hadoop. It is very detailed and has a certain reference value. Friends who are interested must finish reading it.
Start hadoop under the root account (provided that the hadoop account is not a root account), and then switch to the hadoop account after termination, and Permission Denied will appear.
2013-08-06 09 ERROR org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem initialization failed.
Java.io.FileNotFoundException: / opt/data/hadoop/hdfs/name/in_use.lock (Permission denied)
The cause of the exception:
Because root will change the file permissions, use chown-R hadoop:hadoop / opt/data/hadoop/hdfs/* to change the user permissions.
Since slave does not have root@master 's ssh without key to log in, it will not operate the slave machine. If there is any, you can do the corresponding operation on the slave machine.
# View permissions of current folder
[hadoop@master current] $ll-a / opt/data/hadoop/hdfs/name/
Solution:
# stop hadoop cluster
Stop-all.sh
# exit the hadoop account, return to the root account permission, and change the current folder permission to hadoop
[root@master Desktop] # chown hadoop:hadoop / opt/data/hadoop/hdfs/name/current/*
# View permissions of current folder
[root@master Desktop] # ll-a / opt/data/hadoop/hdfs/name/current/
Total dosage 24
Drwxr-xr-x. 2 hadoop hadoop 4096 April 18 10:45.
Drwxrwxr-x. 5 hadoop hadoop 4096 April 18 11:25..
-rw-r--r--. 1 hadoop hadoop 4 April 18 10:45 edits
-rw-r--r--. 1 hadoop hadoop 2226 April 18 10:45 fsimage
-rw-r--r--. 1 hadoop hadoop 8 April 18 10:45 fstime
-rw-r--r--. 1 hadoop hadoop 99 April 18 10:45 VERSION
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