Jobtracker and Tasktracker

Jobtracker and Tasktracker

Jobtracker corresponds to Namenode

Tasktracker corresponds to Datanode

Datanode and Namenode are for data storage.

Jobtracker and Tasktracker are for mapreduce execution.

Several key concepts in MapReduce, MapReduce can be divided into such a few execution clues as a whole:

Jobclient,jobtracker and Tasktracker.

1, Jobclient will be in the client through the Jobclient class will be the application of the configuration parameters packaged into a jar file stored to HDFs,

and submit the path to Jobtracker, then create each task by Jobtracker (i.e. Maptask and Reducetask)

and distribute them to various tasktracker services to perform

2, Jobtracker is a master service, software started after the Jobtracker receive job, is responsible for scheduling the job of each subtask task to run on the Tasktracker,

and monitor them and rerun the task if it is found to have failed tasks. In general, Jobtracker should be deployed on separate machines.

3, Tasktracker is running on multiple nodes of the slaver service. Tasktracker actively communicates with Jobtracker, receives jobs, and is responsible for the direct execution of each task.

Tasktracker all need to run on HDFs's datanode.