HDFS - Block

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File System - Block in HDFS.

The block size can be changed by file.

Block are stored on a datanode and are grouped in block pool



Hdfs Ui Block Information


The location on where the blocks are stored is defined in hdfs-site.xml. Example:



For Hive, see Built-in BLOCKOFFSETINSIDE__FILE virtual column


A typical block size used by HDFS is 128 MB. Thus, an HDFS file is chopped up into 128 MB chunks.

hdfs getconf -confKey dfs.blocksize
# of 128 Mb


See the mover hdfs sub-command to move block replicas across storage types.

hdfs mover



under-replicated block

  • web ui: The overview page gives you this information.

Under Replicated Block


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