Description

Description:

Added below metrics to server status.
(https://docs.mongodb.com/manual/reference/command/serverStatus/#serverstatus.metrics.repl)
1) metrics.repl.stepDown - A document that reports on metrics collected
while performing step down.
2) metrics.repl.stepDown.userOperationsKilled - Tracks the number of user operations killed on step down.
3) metrics.repl.stepDown.userOperationsRunning - Tracks the number of user operations left running on step down.
4) metrics.repl.network.notMasterLegacyUnacknowledgedWrites - Tracks the number of times a legacy unacknowledged write failed due to not master error resulted in network disconnection.
5) metrics.repl.network.notMasterUnacknowledgedWrites - Tracks the number of times an unacknowledged write failed due to not master error resulted in network disconnection.

Engineering Ticket Description:

Add the following metrics to server status:

• repl.stepDown.userWriteOperationsKilled: Write operations killed by stepdown.
• repl.stepDown.userReadOperationsRunning: Read operations left running at stepdown
• repl.network.secondaryLegacyUnacknowledgedWrites: Write operations to a secondary which resulted in a disconnection due to being an unacknowledged write (legacy ops)
• repl.network.secondaryUnacknowledgedWrites: Write operations to a secondary which resulted in a disconnection due to being an unacknowledged write

Add the following logging:

• At stepdown log the number of operations killed and preserved.
• Log when an unacknowledged write results in a disconnection.

Scope of changes

• 4.2
• serverStatus

Impact to Other Docs

MVP (Work and Date)

Resources (Scope or Design Docs, Invision, etc.)