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What does the backup window duration setting mean when configuring an Amazon RDS instance?

Amazon RDS Backup Window Duration

Josh M.
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5 Answers5

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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.

Kuldeep Dangi
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  • Answer above suggest that Duration time is the time window where back up will be taken. Can you confirm this? – Jimmy Feb 19 '19 at 06:36
  • Backup can start at anytime between 5:30 to 6:00. When does the backup finish then? – Alex Oct 14 '21 at 04:26
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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.

Yevgeniy Afanasyev
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It's a time window. The backup will take place at some point in time in that window. It might start at exactly the "start time" but it may occur any time after the "start time" as defined by the "Duration".

Clintm
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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

Josh M.
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Ratan Sharma
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    Yes, I understand that - that's why I highlighted and specifically asked about the `duration` field - what does it mean? A backup could take 2 seconds or an hour. Does duration indicate some sort of sliding scale for when the back up starts? Does it indicated the maximum time a backup is allowed to take? I don't get it... – Josh M. Mar 03 '14 at 15:29
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    I still don't get it :( – Sal Aug 24 '18 at 15:23
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    This answer is incomplete. Can you be more specific about duration? Does it indicated the maximum time a backup is allowed to take? – Jimmy Feb 19 '19 at 06:19
  • Do you mean if backup start time is 12:30 and Duration is 0.5 then at 12:30 a backup will create and at 1:00 it will fetch copy of backup? – Jimmy Feb 19 '19 at 06:29
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From what I understand, the backup will start exactly at the start time that you specify.

The duration is us telling AWS how much time needs to be allocated to perform the backup (I'm guessing so they can internally manage resources?).

This doesn't mean it's a "window" but more communicating to Amazon, 'Hey I think I need x number of hours to do this please.'

Amazon state that even if your backup surpasses this duration - it'll keep going.

Source: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithAutomatedBackups.html

Matt Davey
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