You can suspend specified processes in a scaling group and then perform other operations in the scaling group. This helps you manage the scaling activities in your scaling group in a fine-grained manner. You can also resume suspended processes in a scaling group. Then, the resumed processes can continue to work as expected based on their function logic. This topic describes how to suspend and resume processes in a scaling group. This topic also describes the impacts of suspend and resume operations.
Suspend processes in a scaling group
You can specify a specific ongoing process in a scaling group to suspend. After you suspend the specified process, you can perform other operations in the scaling group. For example, after you suspend the health check process in your scaling group, Auto Scaling stops removing unhealthy instances from the scaling group. After you perform the desired operations, you can manually remove the unhealthy instances from the scaling group.
Before you suspend a process, take note of the following items:
Auto Scaling allows you to suspend multiple processes in multiple scaling groups at the same time. The processes in each scaling group may affect each other.
For example, if you suspend the scale-in process and the health check feature identifies an unhealthy instance in your scaling group, the unhealthy instance cannot be automatically removed from the scaling group.
You can implement only process-level control by suspending processes in a scaling group. If you want to implement instance-level control, we recommend that you enable the instance protection feature for your instances or put your instances into the Protected state.
For example, you can put an instance into the Protected state before you troubleshoot issues in the instance or restart the instance. You can also put an instance into the Protected state to prevent instance release. For detailed operations, see Manually change the status of instances and Put an ECS instance into the Protected state.
Auto Scaling also allows you to suspend multiple processes in a scaling group at the same time. The following table describes the effects after you suspend different types of processes in a scaling group.
Process
Effect
Scale-out
Auto Scaling rejects the following scale-out operations in the scaling group:
Manually add instances to the scaling group.
Rebalance the distribution of instances across multiple zones.
Manually execute scale-out rules or automatically execute scale-out rules based on scheduled tasks or event-triggered tasks if the expected number of instances feature is disabled.
Automatically execute scale-out rules based on event-triggered tasks if the expected number of instances feature is enabled.
NoteIf the expected number of instances feature is enabled, Auto Scaling supports manual execution of scale-out rules or automatic execution of scale-out rules based on event-triggered tasks. However, the number of instances remains unchanged after a scale-out rule is executed. The expected number of instances feature triggers a scale-out only after you resume the scale-out process.
Automatically create instances based on checks on the minimum number of instances.
Automatically create preemptible instances if the supplemental preemptible instance feature is enabled.
Scale-in
Auto Scaling rejects the following types of scale-in operations:
Manually remove instances from the scaling group.
Rebalance the distribution of instances across multiple zones.
Manually execute scale-in rules or automatically execute scale-in rules based on scheduled tasks or event-triggered tasks if the expected number of instances feature is disabled.
Automatically execute scale-in rules based on event-triggered tasks if the expected number of instances feature is enabled.
NoteIf the expected number of instances feature is enabled, Auto Scaling supports the manual execution of scale-in rules or automatic execution of scale-in rules based on scheduled tasks. However, the number of instances in the scaling group remains unchanged. The expected number of instances feature triggers a scale-in only after you resume the scale-in process.
Automatically removes instances from the scaling group based on checks on the maximum number of instances.
Health check
Auto Scaling stops executing health check tasks and does not remove unhealthy instances from the scaling group.
Scheduled task
Auto Scaling does not trigger the execution of the scaling rules specified in scheduled tasks as scheduled.
Event-triggered task
Auto Scaling does not trigger the execution of scaling rules specified in event-triggered tasks when the event-triggered tasks enter the Alert state.
Resume processes in a scaling group
You can specify a suspended process in a scaling group to resume. Then, the resumed process can work as expected based on its function logic. For example, after you resume the health check process in your scaling group, Auto Scaling automatically removes instances that are considered unhealthy from the scaling group.
Before you resume a scaling process, take note of the following items:
After you resume processes in a scaling group, some changes that occur during the suspension may need to be taken into account.
For example, if the expected number of instances is changed during the suspension of a scale-out process, no scale-out operation is complete. After you resume the scale-out process, the expected number of instances feature triggers a scale-out to increase the number of instances in the scaling group to the expected number of instances.
Auto Scaling allows you to resume multiple processes in multiple scaling groups at the same time. The following table describes the effects after you resume different types of processes in a scaling group:
Process
Effect
Scale-out
Auto Scaling resumes scale-out operations, such as manually adding instances, checking the expected number of instances, and checking the minimum number of instances.
If the expected number of instances feature is enabled and the expected number of instances increases during the suspension of the scale-out process, the expected number of instances feature triggers a scale-out to increase the number of instances in the scaling group to the new expected number of instances.
Scale-in
Auto Scaling resumes scale-in operations, such as manually removing instances from the scaling group, checking the expected number of instances, and checking the maximum number of instances.
If the expected number of instances feature is enabled and the expected number of instances decreases during the suspension of a scale-in process, the expected number of instances feature triggers a scale-in to decrease the number of instances in the scaling group to the new expected number of instances.
Health check
Auto Scaling resumes health check operations and removes unhealthy instances from scaling groups.
Scheduled task
Auto Scaling triggers the execution of scaling rules specified in scheduled tasks as scheduled.
Event-triggered task
Auto Scaling triggers the execution of scaling rules specified in event-triggered tasks when the event-triggered tasks enter the Alert state.
Procedure
Log on to the Auto Scaling console.
In the left-side navigation pane, click Scaling Groups.
In the top navigation bar, select the region where Auto Scaling is activated.
On the Scaling Groups page, find the desired scaling group and click Edit in the Actions column.
In the Edit Scaling Group dialog box, perform the following operations to suspend or resume processes:
Suspend processes: Select one or more processes that you want to suspend from the Suspend Process drop-down list.
Resume processes: Remove one or more processes that you want to resume from the Suspend Process text box.
Click OK.
If the scaling strength of your scaling group is not strong, a message that prompts you to confirm your operation appears. You can confirm the operation or go back to the Edit Scaling Group dialog box to modify the parameter settings based on your business requirements.
ImportantIf the scaling strength of your scaling group is not strong, the scaling activities in the scaling group may fail. To prevent scaling failures, we recommend that you go back to the Edit Scaling Group dialog box to increase the scaling strength of your scaling group.
If you do not want to change the parameter settings, click Continue.
If you want to change the parameter settings, click Back to Modify. After you change the parameter settings, click OK.
In the message that appears, click Close.
View the result
On the Scaling Groups page, find the scaling group that you edited and click Details in the Actions column. In the Scaling Group Basic Information section of the Basic Information tab, you can view the suspended or resumed processes in the scaling group.