Forecast how an incremental snapshot chain grows as the protected volume itself grows month over month.
A snapshot chain reaches a steady state where it holds one base copy plus one delta for every day still inside the retention window, so the footprint is the written data multiplied by a factor set by retention and change rate. Growing the source compounds that whole footprint, which is why a 5% monthly increase becomes roughly 1.8x in a year rather than 60%. The price is a user-supplied list price to confirm on the AWS EBS pricing page for your region. Snapshot spend is the line item that grows without anyone changing a setting, and seeing the compounding early is what justifies shortening the retention window before the bill forces it.
Snapshot Growth
footprint(month m) = written GiB x (1 + monthly growth)^m x (1 + (retention days − 1) x daily change rate).
footprint(month m) = written GiB x (1 + monthly growth)^m x (1 + (retention days − 1) x daily change rate). A snapshot chain reaches a steady state where it holds one base copy plus one delta for every day still inside the retention window, so the footprint is the written data multiplied by a factor set by retention and change rate. Growing the source compounds that whole footprint, which is why a 5% monthly increase becomes roughly 1.8x in a year rather than 60%. The price is a user-supplied list price to confirm on the AWS EBS pricing page for your region.
Snapshot spend is the line item that grows without anyone changing a setting, and seeing the compounding early is what justifies shortening the retention window before the bill forces it.
This calculator takes 6 inputs: Written data on the volume today, Daily change rate, Snapshot retention window, Monthly growth of the written data, Forecast horizon, Snapshot price. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
No, less than proportionally. Extending retention adds one daily delta per extra day, not another full copy, so going from 7 to 35 days at a 2% change rate roughly grows the footprint from 1.12x to 1.68x the written data.