Pre-Scaling
Provisioning capacity in advance of a known traffic event rather than relying on autoscaling to react to it.
Autoscaling reacts to load that has already arrived. For a scheduled event — a sale launch, a ticket release, a broadcast moment — the spike arrives faster than instances can start, and the first minutes fail while the system catches up. Those are the minutes that matter most.
Pre-scaling provisions to the expected peak before the event, and treats autoscaling as headroom above the forecast rather than as the mechanism.
What must scale with it, and is routinely forgotten: database connection limits and pooler capacity, downstream third-party quotas (payment processors and identity providers have their own rate limits, and they require advance notice), cache capacity so the working set still fits, queue consumer counts, and cloud service quotas, which frequently need a support request days ahead.
The rest of the readiness plan: cache warming so the event does not begin with a cold cache and a thundering herd; a change freeze for the surrounding period; load testing at forecast peak plus a margin against the actual production configuration; degradation modes pre-agreed with the business, with the flags already in place; and a staffed war room with the runbook and the decision authority present rather than on call.