[HDFS-12131] Add some of the FSNamesystem JMX values as metrics

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.9.0, 3.0.0-beta1, 2.8.3, 2.7.5
• Component/s: hdfs, namenode
• Hadoop Flags: Reviewed
• Assignee: Erik Krogen
• Reporter: Erik Krogen
• Created: 12/Jul/17 22:48
• Updated: 06/Sep/17 22:45
• Resolved: 06/Sep/17 22:29

Description

A number of useful numbers are emitted via the FSNamesystem JMX, but not through the metrics system. These would be useful to be able to track over time, e.g. to alert on via standard metrics systems or to view trends and rate changes:

• NumLiveDataNodes
• NumDeadDataNodes
• NumDecomLiveDataNodes
• NumDecomDeadDataNodes
• NumDecommissioningDataNodes
• NumStaleStorages
• VolumeFailuresTotal
• EstimatedCapacityLostTotal
• NumInMaintenanceLiveDataNodes
• NumInMaintenanceDeadDataNodes
• NumEnteringMaintenanceDataNodes

This is a simple change that just requires annotating the JMX methods with @Metric.