In Hadoop we have mainly 6 configuration files, they are:
core-site.xml
mapred-site.xml
hdfs-site.xml
Masters
Slaves
hadoop-env.sh
core-site.xml:
This file contains the information like, where exactly the Name Node is running and the default port number of Name Node. The default port number of Name Node is 8020.
In the above file 'fs.default.name' is the name of Name Node. The <value> contains the url of Name Node. In this file the Name Node information is Mandatory.
mapred-site.xml:
This file contains the information regarding Job Tracker daemon. In this file Job Tracker Information is mandatory.
hdfs-site.xml:
This file contains the information of block size, replication factor etc.., In this file Replication factor information is mandatory, because when we use a single node cluster, we cannot have the replication factor as 3.
Masters:
This file contains the information about the master nodes. If the Name Node is down, this files tells us which node should be treated as Secondary Name Node.
Slaves:
This file contains the information about slave nodes. Information in the sense, the number of nodes and their names and addresses.
hadoop-env.sh:
This file contains all the environment variables like HADOOP_HOME(hadoop installation directory), JAVA HOME etc..,
