What is the difference between Namenode and Datanode?
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1. NameNode:
– NameNode is the central node in the HDFS architecture and serves as the metadata repository for the file system.
– It keeps track of the directory tree structure, file names, and file-to-block mapping.
– NameNode stores metadata information such as the location of each block in the cluster, file permissions, and replication factor.
– NameNode does not store the actual data blocks but rather maintains metadata information in memory and on disk.
2. DataNode:
– DataNode is responsible for storing and serving data blocks in the HDFS.
– Each DataNode stores a portion of the data blocks in the cluster and replicates them based on the replication factor specified by the NameNode.
– DataNode periodically sends heartbeat signals to the NameNode to report their status and availability.
– DataNode handles read and write requests from clients, including storing new data blocks, replicating blocks, and serving data to clients for reading.