Explanation: Amazon RDS performs maintenance on the DB instance during a user-definable maintenance window. The system may be offline or experience lower performance during that window. The only maintenance events that may require RDS to make the DB instance offline are:
Scaling compute operations
Software patching.
Required software patching is automatically scheduled only for patches that are security and durability related. Such patching occurs infrequently (typically once every few months) and seldom requires more than a fraction of the maintenance window.