rs.stepDown()¶

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Description
Behavior

Description¶

rs.stepDown(stepDownSecs, secondaryCatchUpPeriodSecs)¶

Instructs the primary of the replica set to become a secondary. After the primary steps down, eligible secondaries will hold an election for primary.

The method does not immediately step down the primary. If no electable secondaries are up to date with the primary, the primary waits up to secondaryCatchUpPeriodSecs (by default 10 seconds) for a secondary to catch up. Once an electable secondary is available, the method steps down the primary.

Once stepped down, the original primary becomes a secondary and is ineligible from becoming primary again for the remainder of time specified by stepDownSecs.

For a detailed explanation of the method ‘s execution, see Behavior.

Note

The method is only valid against the primary and throws an error if run on a non-primary member.

The rs.stepDown() method has the following parameters:

Parameter Type Description

stepDownSecs

number

The number of seconds to step down the primary, during which time the stepdown member is ineligible for becoming primary. If you specify a non-numeric value, the command uses 60 seconds.

The stepdown period starts from the time that the mongod receives the command. The stepdown period must be greater than the secondaryCatchUpPeriodSecs.

secondaryCatchUpPeriodSecs

number

Optional. The number of seconds that mongod will wait for an electable secondary to catch up to the primary.

When specified, secondaryCatchUpPeriodSecs overrides the default wait time of 10 seconds.

rs.stepDown() provides a wrapper around the command replSetStepDown.

Behavior¶

Concurrent Operations¶

The rs.stepDown() method attempts to terminate long running user operations that block the primary from stepping down, such as an index build, a write operation or a map-reduce job.

Availability of Eligible Secondaries¶

The method then initiates a catchup period where it waits up to secondaryCatchUpPeriodSeconds, by default 10 seconds, for a secondary to become up-to-date with the primary. The primary only steps down if a secondary is up-to-date with the primary during the catchup period to prevent rollbacks.

If no electable secondary meets this criterion by the end of the waiting period, the primary does not step down and the method errors.

Once the primary steps down successfully, that node cannot become the primary for the remainder of the stepDownSecs period, which began when the node received the method.

Client Connections¶

Starting in MongoDB 4.2, rs.stepDown() method no longer closes all client connections.

In MongoDB 4.0 and earlier, rs.stepDown() method closes all client connections during the step down. Because the disconnect includes the connection used to run the method, you cannot retrieve the return status of the method if the method completes successfully. You can only retrieve the return status of the method if it errors. When running the 4.0 and earlier method in a script, the script should account for this behavior.

Writes During Stepdown¶

Note

All writes to the primary fail during the period starting when the rs.stepDown() method is received until either a new primary is elected, or if there are no electable secondaries, the original primary resumes normal operation.

Writes that were in progress when rs.stepDown() is run are killed. In-progress transactions also fail with "TransientTransactionError" and can be retried as a whole.

The time period where writes fail is at maximum:

secondaryCatchUpPeriodSecs (10s by default) + electionTimeoutMillis (10s by default).

Election Handoff¶

Changed in version 4.0.2: If the parameter enableElectionHandoff is true (default), when a primary steps down from rs.stepDown() (or the replSetStepDown command without the force: true), the stepped-down primary nominates an eligible secondary to call an election immediately. Otherwise, secondaries can wait up to settings.electionTimeoutMillis before calling an election. The stepped down primary does not wait for the effects of the handoff. For more information, see enableElectionHandoff.

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