Major - P3
Added 5 server status metrics:
repl.syncSource.numSelections: The number of times a node attempted to choose a node to sync from among the available sync source options. This occurs if we re-evaluate our sync source, receive an error from the source, or step down.
repl.syncSource.numTimesChoseSame: The number of times a node kept it's original sync source after re-evaluating if its current sync source was optimal.
repl.syncSource.numTimesChoseDifferent: The number of times a node chose a new sync source after re-evaluating if its current sync source was optimal.
repl.syncSource.numTimesCouldNotFind: The number of times a node could not find a sync source when choosing a node to sync from among the available options.
repl.network.replSetUpdatePosition.num: The number of replSetUpdatePosition commands a node sent to its sync source.
Description of Linked Ticket
Ideas for improvements:
Counts of replSetUpdatePosition commands sent
Counts of heartbeats sent to each node
Counts of heartbeats received from each node
Counts getMores sent to sync source
Lag of the updatePositionLastAppliedOpTime that primaries use to commit oplog entries.
Count of elections run
Count of how often we choose a new sync source (even if it's the same one)
Liveness/state view of every other node in the replica set
Scope of changes
Impact to Other Docs
MVP (Work and Date)
Resources (Scope or Design Docs, Invision, etc.)
SERVER-34722 Add new server status metrics about oplog application