Auto Scaling:Limits

Auto Scaling features have the following limits:

• The applications that are hosted on ECS instances or elastic container instances in a scaling group must be stateless and horizontally scalable.
• ECS instances or elastic container instances in a scaling group may be automatically released. We recommend that you do not store information such as sessions, application data, or logs on ECS instances or elastic container instances in a scaling group. If the applications that are hosted on ECS instances or elastic container instances require persistent storage of data, we recommend that you store status information such as sessions on independent ECS instances or elastic container instances, application data in ApsaraDB RDS, and logs in Log Service. For more information, see What is ApsaraDB RDS? and What is Log Service?.
• Auto Scaling cannot automatically add the IP addresses of the ECS instances or elastic container instances to the whitelist that manages access to ApsaraDB for Memcache instances. Therefore, you must manually add the IP addresses of the ECS instances or elastic container instances to the whitelist. For more information, see Configure an IP address whitelist.
• If you delete the ApsaraDB RDS instance, the Application Load Balancer (ALB) server group, the Classic Load Balancer (CLB) instance, or the backend server group of the CLB instance that is associated with a scaling group, the scaling group is automatically disassociated from the deleted resource.
• If a scaling activity that is automatically triggered in a scaling group fails for 30 consecutive days or more, Auto Scaling disables the auto-triggered scaling feature for the scaling group during system inspections and notifies you by using text messages or emails.
  Note If a scaling task fails consecutively, we recommend that you log on to the Auto Scaling console to handle the issue at the earliest opportunity.

The following table describes the limits on the quantities of Auto Scaling resources within a single account.

Item	Quota
Scaling groups in a single region	The quota is determined based on the amount of Auto Scaling resources that you use. For more information, go to Quota Center. Note You can submit a ticket to request a quota increase.
Scaling configurations in a single scaling group
Scaling rules in a single scaling group
ApsaraDB RDS instances that can be associated with a scaling group
CLB instances that can be associated with a scaling group
ALB server groups that can be associated with a scaling group
vServer groups that can be associated with a scaling group
Maximum number of instances that are allowed in a single scaling group
Scheduled tasks in a single region
ECS instances or elastic container instances that can be scaled at a time	500
Instance types in a single scaling configuration	10
Event notifications in a single scaling group	6
Lifecycle hooks in a single scaling group	10