MemberSeptember 23, 2020 at 9:14 pm
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“The first snapshot of a DB instance contains the data for the full DB instance. Subsequent snapshots of the same DB instance are incremental, which means that only the data that has changed after your most recent snapshot is saved.”
>> This is done by AWS to make sure that subsequent backups are faster and will take up less space.
“When automated backups are turned on for your DB Instance, Amazon RDS automatically performs a full daily snapshot of your data (during your preferred backup window) and captures transaction logs (as updates to your DB Instance are made)”
>> This just means that AWS ensures that any backup you choose to restore will contain the complete data at that point-in-time snapshot. If the snapshot is incremental, the data from the last full backup and previous increments will be combined to it to create a full restore of your data. This also means that if you delete the oldest full snapshot, AWS will merge it to the next oldest incremental backup to make it the new full backup.
AWS has a page for the explanation on how it performs RDS backup: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithAutomatedBackups.html
This is also worth a read to grasp the concept of how AWS perform snapshots of EBS volumes: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSSnapshots.html
Let us know if you need further assistance. The Tutorials Dojo team is dedicated to help you pass your AWS exam!
Kenneth Samonte @ Tutorials Dojo