EMERGING TRENDS IN COMPUTING
CLOUD COMPUTING
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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For which of the following operations is NO communication with the NameNode required?
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A client writing a file to HDFS.
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A client requesting the filename of a given block of data.
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A client reading a block of data from the cluster.
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A client reading a file from the cluster.
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Explanation:
Detailed explanation-1: -Answer: The client reading the data from the HDFS filesystem in Hadoop gets the block location from the Namenode and then gets the data from the Datanode.
Detailed explanation-2: -2.1. Hadoop HDFS Data Write Operation. To write a file in HDFS, a client needs to interact with master i.e. namenode (master). Now namenode provides the address of the datanodes (slaves) on which client will start writing the data.
Detailed explanation-3: -HDFS Namenode stores meta-data i.e. number of data blocks, file name, path, Block IDs, Block location, no. of replicas, and also Slave related configuration. This meta-data is available in memory in the master for faster retrieval of data.
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