[HDFS-2510] Add HA-related metrics

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: HA branch (HDFS-1623)
• Fix Version/s: HA branch (HDFS-1623)
• Component/s: datanode, ha, namenode
• Target Version/s: HA branch (HDFS-1623)
• Hadoop Flags: Reviewed
• Assignee: Aaron T. Myers
• Reporter: Aaron T. Myers
• Created: 28/Oct/11 23:19
• Updated: 10/Feb/12 12:55
• Resolved: 09/Feb/12 17:40

Description

Off the top of my head, I can think of:

NN metrics:

• A binary metric for active or standby
• The size of the pending DN message queues
• A timestamp for when the standby NN last read from shared edit log
• The difference between highest generation stamp seen from the shared edit log and the highest generation stamp seen from any DN

It would probably also be useful to have a DN metric which somehow describes which active/standby NNs its talking to, e.g. "times since last communicated with standby/active NNs."

I'm sure there are others as well. Comments strongly encouraged.