Am I going to be charged for having more than one backup on the free tier?

Question

If I'm reading this right, you're allowed _20 GB of storage for database backups and DB Snapshots_ and the smallest database you can have is 20 GB. By default it's creating an automated snapshot once per day, so with the exception of the first backup, every subsequent daily backup is going to be charged at cost to my account?   
  
It's important to understand this but I'd also add comment that it seems like a trap because the defaults for the free account are set up to charge you for 140GB of 7-day rolling automated backups each month. There doesn't seem to be an option to change the backup period (it's always once per day, as opposed to once per week); the only thing that can vary is the retention period. Can you confirm this is all correct?

HalTemp · Answer

RDS Backups are based on EBS Snapshots. EBS snapshots are **incremental**, and don't include unwritten blocks. RDS has a minimum volume size that is allocated, but that doesn't mean that every block is written to. So you could have a 20GB volume, use 5GB of it, change a couple of hundred MB a day, and get through a 7 day cycle without exceeding your free allotment of backup storage. Or you could use all 20GB, but never update it again and you wouldn't exceed your free allotment. Most people who use the t2.micro, especially on the free tier, have tiny databases (well under 1GB) and so they won't ever exceed the included backup storage and have to pay for additional storage. If you need a guarantee not to exceed the included 20GB of backup storage in the free tier, then you can always set retention to 1 day.

Am I going to be charged for having more than one backup on the free tier?

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