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Answer : Short answer - you shouldn't worry about FreeableMemory unless it is became really low (about 100-200 Mb) or significant swapping occur (see RDS SwapUsage metric). FreeableMemory is not a MySQL metric, but OS metric. It is hard to give precise definition, but you can treat it as memory which OS will be able to allocate to anyone who request it (in your case it likely will be MySQL). MySQL have a set of settings which are restricting it's overall memory usage to some cap(you can use something like this to actually calculate it). It's unlikely that your instance will ever hit this limit, due to the fact that in general you never reach max number of connections, but this is still possible. Now going back to "decline" in FreeableMemory metric. For the MySQL most of the memory consume by InnoDB buffer pool (see here for details). RDS instances in there config by default have size for this buffer set to 75% of hosts physical memory - which in your case i...

Answer : Backup window doesn't specifically ask for the time when to start take backup but instead ask for time period in which aws can trigger backup. So basically it's asking for backup window time . That's why it has 2 fields 1. StartTime: When can the process of backup be started. 2. Duration : time window in which process must start to take backup. E.G if I set start time: 5:30 and duration: 30mints Backup can start at anytime between 5:30 to 6:00 . from Working With Backups documentaion Below is the answer for "what if the backup did not fit into a backup window?" If the backup requires more time than allotted to the backup window, the backup continues after the window ends, until it finishes. Below is the answer for "If backup may not fit into the backup window, why do we need a backup window?" The backup window can't overlap with the weekly maintenance window for the DB instance.