Last updated：2021-05-21 17:42:57
The cooldown period is a period during which Auto Scaling cannot execute any new scaling activities after Auto Scaling completes a scaling activity to add or remove Kingsoft Cloud Elastic Compute (KEC) instances. The cooldown period ranges from 120 to 99999 seconds.
No. Auto Scaling does not need to wait for the cooldown period to complete to add manually added KEC instances to a scaling group.
Yes. You can use Auto Scaling for free. However, you must pay for the KEC instances that are automatically or manually added at the normal price.
You can set the maximum number of KEC instances in a scaling group to 10 at most. If you want a scaling group to support more KEC instances, submit a ticket.
Applications running on KEC instances in Auto Scaling must be stateless and support resource scale-out. Auto Scaling can automatically release KEC instances. Therefore, do not store status information such as sessions and relevant data such as database data and logs on the KEC instances in scaling groups. Otherwise, the data is lost when the KEC instances are released.
If your application needs to store status or log information on KEC instances, you can store the information on independent KEC instances.
A KEC instance must meet the following requirements before it can be manually added to a scaling group:
The SLB instance and the scaling group must be in the same VPC.
No. Auto Scaling cannot scale up or down the configurations of KEC instances. Auto Scaling is a service that automatically scales in or scales out KEC instances based on your business needs and policies. Auto Scaling can automatically add KEC instances when your business load grows, and remove KEC instances when your business load drops. Auto Scaling currently does not support scale-up or scale-down. That is, Auto Scaling cannot automatically adjust the CPU, memory, or bandwidth configurations of KEC instances.
Currently, you must use Auto Scaling together with SLB.
You can create two scheduled tasks for your scaling group and specify the expected number of KEC instances in the scaling group respectively for the two scheduled tasks. In this way, you can use one scheduled task to scale out KEC instances at the start of the time period, and use the other scheduled task to scale in KEC instances at the end of the time period.
Auto Scaling provides two removal policies:
Remove Earliest KEC Instances: Preferentially removes the earliest automatically added KEC instance, and then removes the earliest manually added KEC instance after all automatically added KEC instances are removed.
Remove Latest KEC Instances: Preferentially removes the latest automatically added KEC instance, and then removes the latest manually added KEC instance after all automatically added KEC instances are removed.
When a scaling group is disabled, it does not automatically trigger scale activities, but limits on the scaling group still apply.
When a scaling group is disabled, the following activities cannot be triggered:
However, to ensure proper business running, Auto Scaling still impose the following limits on the scaling group:
If the number of KEC instances in the scaling group is less than the minimum number after you manually remove KEC instances, the KEC instances fail to be removed.
If the number of KEC instances in the scaling group is greater than the maximum number after you manually add KEC instances, the KEC instances fail to be added.
No scaling activity is triggered when you manually increase the maximum and minimum numbers of KEC instances in the scaling group.
Removal of manually added KEC instances: The removed KEC instances are no longer managed by the scaling group. However, Auto Scaling does not release the KEC instances or detach them from the SLB instance.
Removal of automatically added KEC instances: The removed KEC instances are released and detached from the SLB instance.
Currently, Auto Scaling does not support projects. You can only attach an SLB instance in the default project to your scaling group.
Assume that Auto Scaling needs to monitor the maximum value of a metric. Auto Scaling collects the value of the specified metric from each KEC instance every 1 minute in each cycle. If the maximum value of the obtained values meets the specified condition in multiple consecutive cycles, Auto Scaling triggers a scaling activity. The number of consecutive cycles can be customized.
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