Hadoop FAQs
Sunday, 10 March 2013
24 Interview Questions & Answers for Hadoop
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What is a JobTracker in Hadoop? How many instances of JobTracker run on a Hadoop Cluster? JobTracker is the daemon service for submitti...
10 comments:
Friday, 8 March 2013
What is the Hadoop MapReduce API contract for a key and value Class?
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◦The Key must implement the org.apache.hadoop.io.WritableComparable interface. ◦The value must implement the org.apache.hadoop.io.Writabl...
What is the use of Combiners in the Hadoop framework?
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Combiners are used to increase the efficiency of a MapReduce program. They are used to aggregate intermediate map output locally on indivi...
3 comments:
Where the Mapper’s Intermediate data will be stored?
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The mapper output (intermediate data) is stored on the Local file system (NOT HDFS) of each individual mapper nodes. This is typically a te...
Can Reducer talk with each other?
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No, Reducer runs in isolation.
How does a NameNode handle the failure of the data nodes?
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HDFS has master/slave architecture. An HDFS cluster consists of a single NameNode, a master server that manages the file system namespace ...
28 comments:
How HDFA differs with NFS?
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Following are differences between HDFS and NAS o In HDFS Data Blocks are distributed across local drives of all machines in a cluster. W...
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