1.

How does the block scanner handle corrupted DataNode blocks?

Answer»

Following are the steps followed by the block scanner when it detects a corrupted DataNode block-

  • Whenever the block scanner comes across a block that is corrupted, the DataNode reports this particular block to the NAMENODE.
  • The NameNode then processes the block and helps to create the replica of the same using the existing corrupted block.
  • The system does not delete the corrupted block until the replication count of the NEWLY created replicas matches with the replication factor which is 3 by default.

This whole process helps HDFS in maintaining the INTEGRITY of the data during read operation PERFORMED by a client.


Discussion

No Comment Found

Related InterviewSolutions