[HDFS-11049] The description of dfs.block.replicator.classname is not clear

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha1
• Fix Version/s: 2.9.0, 3.0.0-alpha2
• Component/s: documentation
• Hadoop Flags: Reviewed
• Assignee: Yiqun Lin
• Reporter: Yiqun Lin
• Created: 25/Oct/16 08:39
• Updated: 27/Oct/16 10:38
• Resolved: 27/Oct/16 07:38

Description

Now the description of the property dfs.block.replicator.classname seems not clearly. The current description:

<property>
  <name>dfs.block.replicator.classname</name>  <value>org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault</value>
  <description>
    Class representing block placement policy for non-striped files.
  </description>
</property>

It seems too simple and the users will not get the other available block placement policies and its usage. For example in HDFS-7541, it introduced a new policy BlockPlacementPolicyWithUpgradeDomain. This policy can be good used in rolling upgrade opeations.

In addition, I don't find other documentations that concretely introducing the existing placement policies. This JIRA foucus on making a improvement for this in file hdfs-default.xml.