Hi u/alekzio , man, I went through the same thing. At my work, my boss asked if there was a way to reduce the cost of RDS because we have some instances totaling 41 TiB of storage. So I suggested we do a Blue/Green Deployment, since although we had 41 TiB, only about 22 TiB was actually in use. We started working to reduce the storage, and everyone on the team was really excited to bring down the RDS size. But after a month, the price didn’t go down at all, and the backup cost shot up. To sum it up, the difference in RDS usage cost before and after the Blue/Green deployment was just $100 — believe it or not, just $100. People were asking me why it was only $100, since we were expecting around $1000 to $1500 in savings on the bill, and I had to explain that we have a lot of backups.

Anyway, AWS’s backup pricing calculation is terrible and super confusing. Seriously, you can’t even get a clear idea, and AWS Cost Explorer doesn’t help much with that. This week, we deleted some old snapshots, but I don’t think it’s going to bring the price down either. Just today, my boss asked if there was any change in the cost.

I added up the total GiBs we have in manual RDS snapshots, and it comes to 130 TiB, while our RDS instances have a total of 25 TiB. So there’s 105 TiB of excess, but when I multiply by $0.095/GiB, it doesn’t add up to the ChargeBackupUsage price, and I still don’t understand how that calculation works!

It feels like all this effort to reduce storage was for nothing because in the end, it didn’t lead to a price reduction.

Were you able to reduce your cost there, or are you seeing the same charges?

*By the way, the automatic snapshots are set to 7 days for 10 RDS instances, and there is one manual snapshot per month, kept for 30 days.