Basic Concepts

AS Group

An AS group consists of a collection of instances that apply to the same scenario. It is the basis for enabling or disabling AS policies and performing scaling actions.

AS Configuration

An AS configuration is a template listing specifications for the instances to be added to an AS group. The specifications include the ECS type, vCPUs, memory, image, login mode, and disk.

AS Policy

AS policies can trigger scaling actions to adjust the number of instances in an AS group. An AS policy defines the condition to trigger a scaling action and the operation to be performed in a scaling action. When the trigger condition is met, the system automatically triggers a scaling action.

Scaling Action

A scaling action adds instances to or removes instances from an AS group. It ensures that the number of instances in the application system is the same as the expected number of instances.

Cooldown Period

To prevent the alarm policy from being frequently triggered, you must set the cooldown period. Cooldown period specifies how long any alarm-triggered scaling action will be disallowed after a previous scaling action is complete. This cooldown period does not apply to scheduled or periodic scaling actions.

For example, the cooldown period is set to 300 seconds, a scheduled policy is specified to trigger a scaling action at 10:32, and a previous scaling action triggered by a alarm policy ends at 10:30. Any alarm-triggered scaling action will be denied during the cooldown period from 10:30 to 10:35, but scheduled scaling actions will still be triggered at 10:32. If the scheduled scaling action ends at 10:36, a new cooldown period starts from 10:36 and ends at 10:41.

Bandwidth Scaling

AS automatically adjusts the bandwidth based on the bandwidth scaling policy you configured. AS can only adjust the bandwidth of pay-per-use EIPs and shared bandwidths, and cannot adjust yearly/monthly bandwidths.