what does "health check replacement" mean here?

Question

reading about scaling policy: https://docs.aws.amazon.com/autoscaling/latest/userguide/as-scaling-simple-step.html

After a scaling activity is started, the policy must wait for the scaling activity or health check replacement to complete and the cooldown period to expire before it can respond to additional alarms.

what is "health check replacement" in this context? its waiting for the scaling activity or "health check replacement" so is "health check replacement" if I manually change the health check? what happens if I edit the "health check while there is a scaling activity

Answer 1

This refers to waiting for one of two types of activities to finish:

Scaling activity refers to automatically launching or terminating instances for a net increase or decrease of capacity.

Health check replacement refers to automatically terminating failed instances and launching new instances to replace them, with no net change in capacity.

While either process is already ongoing, no reaction to further alarms occurs.