Define hadoop archives? What is the command for archiving a group of files in hdfs.

41

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What do you mean by the high availability of a namenode?

34

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What is the difference between nas (network attached storage) and hdfs?

50

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What is a rack awareness algorithm?

58

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What is the problem in having lots of small files in hdfs?

46

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Why rack awareness algorithm is used in hadoop?

41

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Can you change the block size of hdfs files?

45

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What is an identity mapper and identity reducer?

601

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What are the advantages of using mapreduce with hadoop?

588

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What do you know about nlineinputformat?

681

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Why the output of map tasks are stored (spilled ) into local disc and not in hdfs?

662

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What is the role of recordreader in hadoop mapreduce?

730

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What happens when the node running the map task fails before the map output has been sent to the reducer?

646

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Define speculative execution?

713

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Is it legal to set the number of reducer task to zero? Where the output will be stored in this case?

659

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