Example Analysis of HDFS formatting
This article mainly introduces the example analysis of HDFS format, which has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, let the editor take you to understand it.
Anyway, let's take a look at the formatting of HDFS in the new version 2.5.1.
The compiled directory is: ~ / hadoop-2.5.1-src/hadoop-dist/target/hadoop-2.5.1
Did you see a lot of familiar documents when you went in?
For convenience, we set up a soft link as follows:
Ln-s ~ / hadoop-2.5.1-src/hadoop-dist/target/hadoop-2.5.1 hadoop-2.5.1-run
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Root@idc100:~# cd hadoop-2.5.1-run
Root@idc100:~/hadoop-2.5.1-run# ls
Bin hadoop-2.5.1-run lib LICENSE.txt README.txt share
Etc include libexec NOTICE.txt sbin
Root@idc100:~/hadoop-2.5.1-run#
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There is no problem with executing. / bin/hdfs namenode-format.
Then we start with the. / bin/hdfs script to look at the formatting process bit by bit.
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After a long study of shell scripts (not for long, one night, actually)
I won't go into the details of the specific analysis. It's all tears.
Add echo to the shell script to check the value of each variable and the value of export
Anyway, in the end, it is the implementation of this sentence:
--
Through echo, we can see that the end result is execution:
/ usr/lib/jvm/jdk1.7.0_21/bin/java-Dproc_namenode-Xmx1000m-Djava.net.preferIPv4Stack=true-Dhadoop.log.dir=/root/hadoop-2.5.1-src/hadoop-dist/target/hadoop-2.5.1/logs-Dhadoop.log.file=hadoop.log-Dhadoop.home.dir=/root/hadoop-2.5.1-src/hadoop-dist/target/hadoop-2.5.1-Dhadoop.id.str=root-Dhadoop.root.logger=INFO Console-Djava.library.path=/root/hadoop-2.5.1-src/hadoop-dist/target/hadoop-2.5.1/lib/native-Dhadoop.policy.file=hadoop-policy.xml-Djava.net.preferIPv4Stack=true-Dhadoop.security.logger=INFO,RFAS-Dhdfs.audit.logger=INFO,NullAppender-Dhadoop.security.logger=INFO,NullAppender org.apache.hadoop.hdfs.server.namenode.NameNode-format
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