User Guide

Service Overview
What Is AS?
Product Advantages
- Advantages
- Scaling Resources Based on Demand
- Using ELB with AS
Lifecycle
Use Restrictions
Related Services
Basic Concepts
- AS Group
- AS Configuration
- Scaling Actions
Best Practice
Deploying the Auto Scaling Discuz Forum Website
Quick Start
Wizard-based Process of Using AS
Creating an AS Group Quickly
AS Management
AS Groups
- Creating an AS group
- (Optional) Adding a Load Balancer to an AS Group
- Replacing an AS Configuration in an AS Group
- Enabling an AS Group
- Disabling an AS Group
- Modifying an AS Group
- Deleting an AS Group
AS Configurations
- Creating an AS configuration
- Using an Existing ECS to Create an AS Configuration
- Using a New Specifications Template to Create an AS Configuration
- Copying an AS Configuration
- Deleting an AS Configuration
Scaling Actions
- Dynamically Expanding Resources
- Expanding Resources as Planned
- Manually Expanding Resources
- Configuring an Instance Removal Policy
- Viewing a Scaling Action
- Managing Lifecycle Hooks
- Managing Scaling Policies
- Configuring Instance Protection
Monitoring AS Groups and Instances
- Checking Instance Health Status
- Configuring Notification for an AS Group
- Recording AS Resource Operations
- Marking AS Groups and ECSs
- Monitoring Metrics
- Viewing Metrics
- Setting Monitoring Alarm Rules
FAQs
General
- What Is AS?
- What Are Restrictions on Using AS?
- Does an Abrupt Change on Monitoring Indicator Values Cause an Incorrect Scaling Action?
- Are ELB and Cloud Eye Mandatory for AS?
- How Many AS Policies and AS Configurations Can I Create and Use?
AS Group
- What Can I Do If the AS Group Fails to Be Enabled?
- Why Does Not the ELB Health Check Used by an AS Group Take Effect Immediately?
- What Operation Will Be Suspended After An AS Group Is Disabled?
- What Is Health Check Grace Period?
- How Can I Handle an AS Group Exception?
AS Policy
- How Many AS Policies Can Be Enabled?
- What Can I Do If an AS Policy Fails to Be Enabled?
- What Is a Cooldown Period? Why Is It Required?
- What Are the Conditions to Trigger an Alarm in the AS Policy?
- What Will Monitoring Metrics for an AS Group Be Affected If VM Tools Are Not Installed on ECSs?
Instance
- How Do I Delete an ECS Created During a Scaling Action?
- Will the Application Data on an Instance Be Retained After the Instance Is Removed from an AS Group and Deleted?
- How Do I Prevent ECSs from Being Removed from an AS Group Automatically?
- How Should I Handle Abnormal Instances in an AS Group?
- What Is the Expected Number of Instances?
- Why Do Instances in an AS Group Frequently Fail Health Checks and Are Deleted And Then Created Repeatedly?
- Can Instances That Have Been Added Based on an AS Policy Be Automatically Deleted When They Are Not Required?
Others
- What Can I Do to Enable My Application to Be Automatically Deployed on an Instance?
- How Can I Enable Automatic Initialization of EVS Disks of Instances That Have Been Added in a Scaling Action to an AS Group?
- Why Cannot I Use a Key File to Log In to an ECS?
- How Does Cloud-Init Influence the AS Service?
- Do I Need to Configure an EIP in an AS Configuration When A Load Balancer Has Been Enabled in an AS Group?
Change History

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Help Center
FAQs
Instance
What Is the Expected Number of Instances?

What Is the Expected Number of Instances?

The expected number of instances refers to the number of ECSs that are expected to run in an AS group. It is between the minimum number of instances and the maximum number of instances. You can manually change the expected number of instances or change it based on the scheduled, periodic, or alarm policies.

After you set the expected number of instances when creating an AS group and the number is not 0, a scaling action will be automatically triggered to add the required number of ECSs to the AS group.

Manually adjust the expected number of instances: After you manually change the number of expected instances, the current number of instances is not consistent with the expected number. As a result, a scaling action is triggered to adjust the number of instances in the AS group to the expected number.

Change the number of expected instances by scaling policies: After a scaling policy which adds two instances to an AS group is triggered, the system will add two to the expected number of instances. In this case, the system triggers a scaling action to add two instances so that the number of instances in the AS group is the same as the expected number.

Parent topic: Instance