Hadoop Common Configuration Meaning Memo

A number of configuration parameters are listed

Where red is configured to have parameters configured

Parameter value Comment

Fs.default.name	The URI of the NameNode.	HDFS://Host name/
Dfs.hosts/dfs.hosts.exclude	License/Deny Datanode list.	If necessary, use this file to control the list of licensed Datanode.
Dfs.replication	Default: 3	Score for data replication
Dfs.name.dir	Example:/home/username/hadoop/namenode Default:/tmp	When this value is a comma-delimited list of directories, the NameTable data will be copied to all directories for redundant backups.
Dfs.data.dir	Example:/home/username/hadoop/datanode Default:/tmp	When this value is a comma-separated list of directories, the data will be stored in all directories, usually distributed on different devices.
Mapred.system.dir	Map/reduce the HDFS path to the framework storage system files. Like/hadoop/mapred/system/.	This path is the path under the default file system (HDFS) and must be accessible from both the server and the client.
Mapred.local.dir	A comma-delimited list of paths under the local file system, where temporary data is stored map/reduce.	Multipath helps take advantage of disk I/O.
Mapred.tasktracker. {Map|reduce}.tasks.maximum	The maximum number of map/reduce tasks that can be run on a tasktracker, and these tasks will run concurrently.	The default is 2 (2 map and 2 reduce), which can be changed according to the hardware condition.
Mapred.job.tracker	The host (or IP) and port of the Jobtracker.	Host: Port.
Mapred.hosts/mapred.hosts.exclude	License/Deny Tasktracker list.	If necessary, use this file to control the list of licensed Tasktracker.
Hadoop.job.history.user.location	Default: Mapred.output.dir/_logs/history can also be set to none to deactivate	History file record directory for the job

Conf/slaves write the machine name or IP of all slave

Namenode Remember that each file is mapped into a blockid. Each blockid corresponding block is copied to a different machine.

The default block for Hadoop is 64MB

See if Namenode starts: http://localhost:50070/

See if Jobtracker starts: http://localhost:50030/

Reprint: http://eryk.iteye.com/blog/792962