Big data series (2) HDFS writing process and reading process

Two problems

• The data block is generally set to 128M
• Today's NameNode has two nodes that solve today's single point problem

HDFS write process

• The client initiates a data write request to the NameNode
• Write to the DataNode node in blocks, and the DataNode automatically completes the copy backup
• The DataNode reports to the NameNode that the storage is complete, and the NameNode informs the client
  
  

HDFS read process

• The client initiates a data read request to the NameNode
• NameNode finds the closest DataNode node information
• The client downloads files in chunks from the DataNode