Your cluster Mapreduce V1 (MVR1). What determines where blocks are return into HDFS client application?

Question

Options

• Athe client writes immediately to data nodes at random
• BThe client immediately to data nodes based on the clusters rack locality settings
• CThe clients sends the data to the name node, which then writes those blocks to the data nodes
• DThe client queries the name node, which returns information on which data nodes to use. Then client

• A
  3% (1)
• B
  9% (3)
• C
  15% (5)
• D
  74% (25)

Explanation

For each block, the Client consults the Name Node. HDFS is the primary distributed storage used by Hadoop applications. A HDFS cluster primarily consists of a NameNode that manages the file system metadata and DataNodes that store the Clients contact NameNode for file metadata or file modifications and perform actual file I/O directly with the DataNodes. The NameNode is the centerpiece of an HDFS file system. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. It does not store the data of these files itself. Client applications talk to the NameNode whenever they wish to locate a file, or when they want to add/copy/move/delete a file. The NameNode responds the successful requests by returning a list of relevant DataNode servers where the data lives.

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