Starting with MongoDB 4.2, there are now five verbosity log levels, each revealing increasing amounts of information. In MongoDB 4.0.6, you can now set a threshold on the maximum time it should take for data to replicate between members of a replica set. It's now possible to get the information from the MongoDB log file if that time is exceeded.
A further enhancement to diagnostics capabilities includes additional fields that are added to the output of the db.serverStatus() command that can be issued from a Mongo shell.
