问题
What does the backup window duration setting mean when configuring an Amazon RDS instance?
回答1:
If you are using automated backup for a DB instance, by enabling backups. The Backup Window time is the time in which the instance’s back up will be created.
Start time : This means the time of the day you configure the backup to take place.
Duration : This is the time window where back up will be taken - Default is 30 minutes.
For details : http://aws.typepad.com/aws/2011/03/amazon-rds-maintenance-windows-shortened.html
回答2:
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.
回答3:
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.
来源：https://stackoverflow.com/questions/22148001/amazon-rds-instance-backup-window-duration