Cool-down time refers to a period during which Auto Scaling cannot execute any new scaling activity after another scaling activity is executed successfully in a scaling group.
During cool-down time, the scaling activity requests from CloudMonitor alarm tasks are rejected. Other tasks, such as manually executed scaling rules and scheduled tasks, can immediately trigger scaling activities without waiting for the cool-down time to expire.
During cool-down time, only the corresponding scaling group is locked. Scaling activities set for other scaling groups can be executed.
When the cool-down time specified by the scaling rule and the default cool-down time for the scaling group overlap, the former takes precedence over the latter.
When more than one instance is added to or removed from a scaling group, the cool-down time starts after the last instance is added to or removed from the scaling group.
As long as a scaling activity adds or removes one or more ECS instances, the cool-down time begins when the last ECS instance is added or removed.
If a scaling activity does not successfully add or remove any ECS instances, the cool-down time will not start.
After a scaling group is re-enabled after being disabled, the cool-down time is no longer in effect. For example, if a scaling activity is completed at 12:00 PM and the cool-down time is 15 minutes, the scaling group is then disabled and re-enabled, and the cool-down time is no longer in effect. If a request for triggering a scaling activity is sent at 12:03 PM from the CloudMonitor, the requested scaling activity is executed immediately.