How many mappers required for a map reduce, job determine on a cluster running map reduce V1 (MRv1)?

Question

Options

• AThe number mappers is equal to no of input splits calculated by client submitting
• Bthe developer specifies the number in the job configuration
• Cthe jobtracker chooses the number based on no of available nodes
• DThe number of mappers is calculated by namenode based on the number of HDFS blocks in the files

• A
  5% (1)
• B
  9% (2)
• C
  5% (1)
• D
  82% (18)

Explanation

The HDFS namenode has the following responsibilities: * Coordinating file operations. The namenode directs application clients to datanodes for read operations, and allocates blocks on suitable datanodes for write operations * Namespace management. * Maintaining overall health of the file system.

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