Answer / Lokendra

Debugging Hadoop code involves understanding the MapReduce or YARN programming model and familiarity with tools such as: 1) Hadoop's built-in logging (e.g., logs produced by JobTracker, TaskTracker, NameNode, DataNode). 2) Web UIs provided by Hadoop (e.g., job tracking, cluster browsing). 3) Custom debugging techniques like printing intermediate results to the log or using specialized tools like VisualVM.

Main Components of Hadoop?

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What is a Secondary Namenode? Is it a substitute to the Namenode?

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What are the default configuration files that are used in hadoop?

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What are the main components of a Hadoop Application?

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What is Safemode in Apache Hadoop?

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How we can change Replication factor when Data is on the fly?

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What are combiners and its purpose?

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What is the best hardware configuration to run Hadoop?

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Explain what if rack 2 and datanode fails?

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How to enable recycle bin in hadoop?

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Suppose Hadoop spawned 100 tasks for a job and one of the task failed. What will Hadoop do?

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How to come out of the insert mode?

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