Autoscale economics

A fleet sized for the evening peak is paid for at peak size all day, even at 4 a.m. Autoscaling lets the bill follow the traffic instead — you pay for instance-hours, so fewer servers in quiet hours means a smaller bill. How much you save depends on how far the peak is above the average; flat traffic saves almost nothing. Every safety setting has a price — a higher minimum, more headroom and a slower scale-in all cost money, and a maximum caps the bill but turns away anything above it. Known peaks can be scheduled ahead of time, and the steady base that always runs can be bought cheaper with a long-term commitment.

Use when

Traffic with a clear daily or weekly rhythm, where the peak is far above the average · A stateless tier whose fleet is sized for the peak all day · Peaks you can predict — a schedule adds capacity before they arrive

Avoid when

Flat traffic — the fleet barely changes, so there is little to save · Spikes shorter than an instance's start-up time — you pay for instances that arrive too late · Stateful tiers such as the primary database

Trade-offs

A higher minimum and more headroom lower the risk of slow requests, at a price paid every hour · Slow scale-in avoids flapping but keeps paying for capacity after the peak has passed · A maximum caps the bill and the capacity together — traffic above it is turned away · Commitments cut the price of the always-on base, but are paid whether or not it is used

Requires

Autoscaling, How cloud billing works