Scaling Actions

A scaling action adds or removes instances to or from an AS group so that the number of instances in the AS group is the same as the expected number for proper service running.

A scaling action is triggered when the number of instances in an AS group is not the same as the expected number. This occurs when the condition specified by an AS policy is met or after you manually change the expected number of instances.

• When the condition specified by an AS policy is met, AS changes the expected number of instances according to the value or percentage specified in the AS policy. In this case, the expected number of instances is inconsistent with the actual number, triggering a scaling action.
• After you manually change the expected number of instances, it becomes inconsistent with the actual number of instances in the AS group, and a scaling action is triggered.

The following describes the expected number of instances (Expected Instances) and its related concepts.

• Expected Instances is the expected number of instances in an AS group.
• Min. Instances or Max. Instances are the minimum or maximum number of instances in an AS group.

  The expected number of instances must fall between the minimum and maximum.

• Cooling Duration is the duration for cooling a scaling action.

  The system begins to count the cooling duration after a scaling action is triggered. During the cooling duration, the AS group denies scaling actions triggered by an alarm policy. Other AS policies, including periodic and scheduled policies, are not affected.