[HDFS-12932] Fix confusing LOG message for block replication

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.8.3
• Fix Version/s: 3.1.0
• Component/s: hdfs
• Assignee: Chao Sun
• Reporter: Chao Sun
• Created: 15/Dec/17 23:05
• Updated: 20/Dec/17 17:56
• Resolved: 20/Dec/17 17:11

Description

In our cluster we see large number of log messages such as the following:

2017-12-15 22:55:54,603 INFO org.apache.hadoop.hdfs.server.namenode.FSDirectory: Increasing replication from 3 to 3 for <HDFS file>

This is a little confusing since "from 3 to 3" is not "increasing". Digging into it, it seems related to this piece of code:

    if (oldBR != -1) {
      if (oldBR > targetReplication) {
        FSDirectory.LOG.info("Decreasing replication from {} to {} for {}",
                             oldBR, targetReplication, iip.getPath());
      } else {
        FSDirectory.LOG.info("Increasing replication from {} to {} for {}",
                             oldBR, targetReplication, iip.getPath());
      }
    }

Perhaps a oldBR == targetReplication case is missing?