If you use AS for the first time, it is recommended that you follow the wizard-based process to create an AS group, AS configuration, and AS policy.
ECS types supported by different AZs may vary. When creating an AS group, you must choose a proper AS configuration according to the ECS type supported by the AZs used by the AS group.
Parameter |
Description |
Example Value |
---|---|---|
Name |
Specifies the name of the AS group to be created. The name contains 1 to 64 characters and consists of only letters, digits, underscores (_), and hyphens (-). |
N/A |
Max. Instances or Min. Instances |
Specifies the maximum or minimum number of instances in an AS group. |
10 or 5 |
Expected Instances |
Expected Instances is the expected number of instances in an AS group. After an AS group is created, you can change this value, which will trigger a scaling action. |
6 |
Cooldown Period |
Specifies a period of time after each scaling action is complete. During the cooldown period, scaling actions triggered by alarms will be denied. Scheduled and periodic scaling actions are not restricted.
NOTE:
|
300s |
AZ |
A physical region where resources use independent power supplies and networks. AZs are physically isolated but interconnected through an internal network. To enhance application availability, the system evenly distributes your instances between AZs if multiple AZs have been selected. |
N/A |
VPC |
Provides a network for your instances. All instances in an AS group belong to the same VPC. |
N/A |
Subnet |
By default, only the instances in the same VPC subnet can communicate with each other. If you select multiple subnets, the system binds multiple NICs to an instance that is automatically added by the scaling action to the AS group. The first NIC you selected works as the primary NIC, and the remaining NICs as extended ones. You can select up to five subnets. |
N/A |
Security Group |
Controls instance access within or between security groups by defining access rules. This enhances instance security. |
N/A |
Load Balancing |
This parameter is optional. A load balancer automatically distributes access traffic to all instances in an AS group to balance their service load. It enables higher levels of fault tolerance in your applications and expands application service capabilities.
When using ULB, configure the following parameters:
|
N/A |
Health Check Method |
When a health check detects a faulty instance, AS removes the faulty instance from the AS group and adds a new one. The health check is implemented using any of the following methods:
|
N/A |
Health Check Interval |
Specifies the health check period for an AS group. You can set a proper health check interval, such as 10 seconds, 1 minute, 5 minutes, 15 minutes, 1 hour, and 3 hours based on the site requirements. |
5 minutes |
Health Check Grace Period |
Specifies the grace period for instance health check. The unit is second and value range is 0 to 86400. The default value is 600. The health check grace period starts after an instance is added to an AS group and enabled. The AS group will start checking status of the instance only after the grace period ends. This parameter is available only when ELB health check mode is selected for the AS group. |
600s |
Instance Removal Policy |
Specifies the priority for removing instances from an AS group. If specified conditions are met, scaling actions are triggered to remove instances. AS supports the following instance removal policies:
NOTE:
|
N/A |
Release EIP on Instance Removal |
If EIP has been selected in an AS configuration for an AS group, an EIP is automatically bound to the instance added by a scaling action to the AS group. If you select the check box before Yes, the EIP bound to the instance is released when the instance is removed from the AS group. Otherwise, the system unbinds the EIP from the instance but does not release it when the instance is removed from the AS group. |
N/A |
On the AS Policy tab, click Add AS Policy.
For details, see section Configuring Notification for an AS Group.
For details, see section Marking AS Groups and ECSs.
After the AS group is created, its status changes to Enabled.