RDS Snapshot Chain - Automatic Backups Vs Manual Snapshots

Question

Hello,

If an RDS customer is using both Automatic Backups and Manual Snapshots as part of their protection strategy of an RDS Instance - does each snapshot type for an RDS Database have a separate initial full backup (i.e. one full for automatic and one full for manual) ?

It would also be helpful to know if any subsequent Manual RDS snapshots (in between daily automatic backups) are incremental from the last automatic or the last manual snapshot.

Our docs don't talk about the relationship of backup chains in regards to automatic vs manual on RDS - so this will be helpful information to have.

Thanks!

Accepted Answer

Any snapshot created , be it manual or automated is incremental , as it will work in the following way:
When the snapshot process starts, it will check if the current underlying storage volume has a previous snapshot, to calculate the difference, the blocks that has been modified, and it will backup only the ones that changed since the previous snapshot
So it does not matter whether it is manual or automated
The only exception is any event where the underlying storage may have changed, like A Multi AZ Failover, a Multi AZ to Single AZ change, or some storage modifications
In that case the next snapshot will be a full one

However, Unlike automated backups, manual snapshots aren't subject to the backup retention period.i.e. Snapshots don't expire. So although they are incremental during creationg, they would be sufficient by itself to restore the database until the point of snapshot.

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

RDS Snapshot Chain - Automatic Backups Vs Manual Snapshots

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