HDFS - Block

1 - About

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

3 - Management

3.1 - Info

3.2 - Location

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


3.2.1 - Offset

3.3 - Size

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


  • From the command line:

hdfs getconf -confKey dfs.blocksize

# of 128 Mb

3.4 - Move

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

hdfs mover

3.5 - Failure

3.5.1 - Under-replicated

under-replicated block

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

3.5.2 - Missing

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