[HDFS-13812] Fix the inconsistent default refresh interval on Caching documentation

• Type: Improvement
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 2.9.1
• Fix Version/s: 2.10.0, 3.2.0, 2.9.2, 3.0.4, 2.8.5, 2.7.8, 3.1.2
• Component/s: documentation
• Hadoop Flags: Reviewed
• Assignee: Hrishikesh Gadre
• Reporter: David Mollitor
• Created: 09/Aug/18 13:51
• Updated: 05/Sep/18 05:18
• Resolved: 05/Sep/18 04:56

Description

dfs.namenode.path.based.cache.refresh.interval.ms

The NameNode will use this as the amount of milliseconds between subsequent path cache rescans. This calculates the blocks to cache and each DataNode containing a replica of the block that should cache it.

By default, this parameter is set to 300000, which is five minutes.

https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/CentralizedCacheManagement.html

However, this default value was change in HDFS-6106 to 30 seconds. Please update docs.

Issue Links

• is related to: HDFS-5386 Add feature documentation for datanode caching.
• is related to: HDFS-6106 Reduce default for dfs.namenode.path.based.cache.refresh.interval.ms