We have two line items for continuous backup on each invoice, at two different rates. We are in AWS for storage in MongoDB Atlas. Can someone help explain why there’s two rates here? I’d think tiers but the GB/day on either of them throughout the months doesn’t hit a set capacity, it’s like both are actively growing throughout the month:
Couple examples direct from different month invoices:
Sept 2023:
| Atlas Continuous Cloud Backup Storage - AWS | 2,757.384 GB days @ $0.032877 / GB day | $90.60 |
|---|---|---|
| Atlas Continuous Cloud Backup Storage - AWS | 95.282 GB days @ $0.016438 / GB day | $1.57 |
Last month:
| Atlas Continuous Cloud Backup Storage - AWS | 2,078.956 GB days @ $0.024658 / GB day | $51.25 |
|---|---|---|
| Atlas Continuous Cloud Backup Storage - AWS | 2,668.206 GB days @ $0.032877 / GB day | $87.74 |
We store around 35 snaps at any time, each around 22GB. Total size maybe ~750GB. Who knows the oplog size though, but by the docs it says general backup storage is charged at 0.14/GB/mth in AWS, so $0.004603/GB/day, * 750 * 365/12 and we’d expect to see $103/mth or so from backup storage. Instead we see continuous backup line items like these at a nebulous rate.
I was trying to determine how we can reduce our backup storage charges without blindly making changes, but the calculations shown in the docs don’t seem to match anything here. Continuous backup docs show for over 500GB stored, we’d be looking at 0.25/GB/mth, but at this rate and 750GB we’d expect $187/mth, which is more than we’re being charged. And where does this 2000GB+ figure come from, why are there multiples with different GB figures on each.
Ideally I’d like to know the cost impact of reducing our point in time restore window from 7 days down to 3, and the cost impact of changing our hourly snap retention as well. Any clarification of how the billing for continuous backup works would be so helpful and appreciated!