Hadoop common configuration description Memorandum

Lists many configuration parameters.

 

The red configuration is required.

 

Parameter Value remarks

FS. Default. Name	The uri of the namenode.	HDFS: // host name/
DFS. hosts/dfs. Hosts. Exclude	List of allowed/denied datanode.	Use this file to control the licensed datanode list if necessary.
DFS. Replication	Default Value: 3	Data Replication score
DFS. Name. dir	Example:/home/username/hadoop/namenode Default Value:/Tmp	When this value is a comma-separated directory list, the nametable data will be copied to all directories for redundant backup.
DFS. Data. dir	Example:/home/username/hadoop/datanode Default Value:/tmp	When this value is a comma-separated directory list, data is stored in all directories and usually distributed across different devices.
Mapred. system. dir	HDFS path of the MAP/reduce framework storage system file. For example,/hadoop/mapred/system /.	This path is the path under the default file system (HDFS) and must be accessible from both the server and client.
Mapred. Local. dir	List of comma-separated paths in the local file system, where MAP/reduce temporary data is stored.	Multi-path facilitates the use of disk I/O.
Mapred. tasktracker. {map | reduce}. Tasks. Maximum	The maximum number of MAP/reduce tasks running on a tasktracker. These tasks run simultaneously.	The default value is 2 (2 maps and 2 reduce), which can be changed based on hardware conditions.
Mapred. Job. Tracker	The host (or IP) and Port of jobtracker.	HOST: Port.
Mapred. hosts/mapred. Hosts. Exclude	Permit/deny tasktracker list.	Use this file to control the authorized tasktracker list if necessary.
Hadoop. Job. History. User. Location	Default Value: mapred. Output. DIR/_ logs/History You can also set it to none to disable it.	Job history file directory

 

Conf/slaves write the name or IP address of all slave machines

 

Namenode remembers the blockid mapped to each file. The block corresponding to each blockid is copied to a different machine for additional parts.

The default hadoop block is 64 MB.

 

Check whether namenode is Enabled: http: // localhost: 50070/

Check whether jobtracker is started: http: // localhost: 50030/