[HDFS-10963] Reduce log level when network topology cannot find enough datanodes.

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.8.0, 3.0.0-alpha2
• Labels: supportability
• Target Version/s: 2.8.0
• Hadoop Flags: Reviewed
• Assignee: Xiao Chen
• Reporter: Xiao Chen
• Created: 05/Oct/16 06:07
• Updated: 06/Oct/16 18:34
• Resolved: 06/Oct/16 12:23

Description

Credit to qwertymaniac who reported this.

The change made by HDFS-10320 now causes all 1-rack cluster to keep printing below:
WARN org.apache.hadoop.net.NetworkTopology
Failed to find datanode (scope="" excludedScope="/default").

This was added in HDFS-10320 to replace an exception that caused NN terminate. A warn log was added. But thinking closely, this should be debug to reduce confusion.