Hi!
We upgraded our replicasets to MongoDB 6.0.20 last week. Since the upgrade, the logs of some of our secondaries have been filled with lines like this (approximately 160MB/hour):
{"t":{"$date":"2025-01-21T16:21:04.550+00:00"},"s":"I", "c":"REPL", "id":3873113, "ctx":"ReplCoordExtern-22","msg":"Cannot select sync source which is not ahead of me","attr":{"syncSourceCandidate":"other-secondary-mongo:27017","syncSourceCandidateLastAppliedOpTime":{"ts":{"$timestamp":{"t":1737476461,"i":118}},"t":286},"lastOpTimeFetched":{"ts":{"$timestamp":{"t":1737476464,"i":320}},"t":286}}}
This appears to be related to the changes in SERVER-62921 which moved these messages from debug to info.
As far as I can tell, the replicaset is otherwise performing as expected. We have monitoring set up with mongodb.com which is not reporting any replication lag or other concerns. Our applications using the replicaset also appear unaffected.
Is there a configuration issue which could be causing these incessant logs?
The data in the replicaset is very small. I wiped one of the secondaries completely and allowed it to resync as a test, but this did not help.
Any ideas of where to look for a resolution?
Thanks