capacity-planning
Capacity Planning
Autoscaling handles the minutes-to-hours timescale of load fluctuation. Capacity planning handles the weeks-to-months timescale where the thing you're short on isn't compute headroom but lead time — a database that needs a resize scheduled during a maintenance window, a quota increase that takes two weeks to approve, a new region that takes a quarter to stand up. Autoscaling can't add capacity that doesn't exist yet in the account, the budget, or the vendor relationship.
The recurring failure is planning for the average and getting surprised by the peak. Average load tells you what the system does most of the time; it tells you nothing about whether it survives Black Friday, a viral moment, or the batch job that runs once a quarter.
Plan for the peak, not the average — and start before you need it.