Wednesday, February 19, 2014

What is the namenode startup process steps?


  • Namenode enters Safemode
    • Replication does not occur in Safemode
  • Each Datanode sends Heartbeat 
  • Each Datanode sends Blockreport
    • Lists all HDFS data blocks
  • Namenode creates Blockmap from Blockreports
  • Namenode exits Safemode
  • Replicate any under-replicated blocks 

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