This topic describes the feature and quantity limits of Auto Scaling.

Feature limits

Auto Scaling has the following feature limits:
  • Auto Scaling can automatically scale the number of Elastic Compute Service (ECS) instances in a scaling group, but cannot automatically upgrade or downgrade configurations of ECS instances, such as vCPUs, memory, and bandwidth.
  • Applications deployed on ECS instances in a scaling group must be stateless and horizontally scalable.
  • ECS instances in a scaling group can be automatically released. We recommend that you do not store information such as sessions, application data, or logs on ECS instances in a scaling group. If applications deployed on these ECS instances require data to be stored, store status information such as sessions on independent ECS instances, store application data in ApsaraDB RDS, and store logs in Log Service. For more information, see What is ApsaraDB RDS? and What is Log Service?.
  • Auto Scaling cannot automatically add ECS instances to the whitelist of an ApsaraDB for Memcache instance. You must manually add these ECS instances to the whitelist. For more information, see Set IP firewall.

Quantity limits

The following table describes the quantity limits that apply to Auto Scaling within a single account.
Item Limit
Scaling groups in a region The quota is based on your resource usage of Auto Scaling. Go to the Quota Center to view the quota.
Note You can submit a ticket to apply for a quota increase.
Scaling configurations in a scaling group
Scaling rules in a scaling group
RDS instances that can be associated with a scaling group
Server Load Balancer (SLB) instances that can be associated with a scaling group
Application Load Balancer (ALB) server groups that can be associated with a scaling group
vServer groups that can be associated with a scaling group
ECS instances that can be configured for a scaling group
Scheduled tasks in a region
ECS instances that can be added to or deleted from a scaling group during a scaling activity 500
Instance types in a scaling configuration 10
Event notifications in a scaling group 6
Lifecycle hooks in a scaling group 6