- What's New
- Function Overview
- Service Overview
- Getting Started
- User Guide
- Best Practices
-
API Reference
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
APIs
- AS Groups
- AS Configurations
- Instances
-
AS Policies
- Creating an AS Policy
- Creating an AS Policy (V2)
- Modifying an AS Policy
- Modifying an AS Policy (V2)
- Querying AS Policies Bound to an AS Group
- Querying AS Policies Bound to a Scaling Resource (V2)
- Querying AS Policies (V2)
- Querying an AS Policy
- Querying an AS Policy (V2)
- Executing, Enabling, or Disabling an AS Policy
- Deleting an AS Policy
- Batch Managing AS Policies
- AS Policy Execution Logs
- Scaling Action Logs
- Quotas
- Notifications
- Lifecycle Hooks
- Tags
- Planned Tasks
- API Version Query
- Application Examples
- Permissions and Supported Actions
- Appendix
- Change History
- SDK Reference
-
FAQ
-
General
- What Are Restrictions on Using AS?
- Must I Use AS Together With ELB and Cloud Eye?
- Is AS Billed?
- Will an Abrupt Change in Monitoring Metric Values Trigger an Unnecessary Scaling Action?
- How Many AS Policies and AS Configurations Can I Create and Use?
- Can AS Automatically Scale Up or Down vCPUs, Memory, and Bandwidth of ECSs?
- What Is an AS Quota?
- How Do I Fix the Error "The key pair does not exist" When I Connect to an Instance?
- What Types of EIP and Shared Bandwidths Can Be Adjusted by AS?
- What Types of ECS and HECS Instances Can Be Scaled by AS?
- If the OS of an ECS Instance in an AS Group Is Upgraded, Can AS Automatically Add Instances with the Newest OS During the Next Scale-out Action?
- Can AS Add Yearly/Monthly ECS Instances When It Scales Out an AS Group?
- Can AS Increase Bandwidths as Required?
- AS Group
-
AS Policy
- How Many AS Policies Can I Enable?
- What Are the Conditions to Trigger an Alarm-based AS Policy?
- What Is a Cooldown Period and Why Is It Required?
- Can AS Scale Capacity Based on Custom Monitoring by Cloud Eye?
- What Monitoring Metrics for an AS Group Will Be Affected If VM Tools Are Not Installed on the Instances in the Group?
- What Can I Do If an AS Policy Fails to Be Enabled?
- How Do I Install the Agent on Instances in an AS Group to Use Agent Monitoring Metrics?
-
Instance
- How Do I Prevent Instances Manually Added to an AS Group from Being Automatically Removed?
- When There Are Multiple Flavors Included in the AS Configuration of an AS Group, What Order Are the Flavors Selected in During Scale-out Events?
- When an Instance Is Removed from an AS Group and Deleted, Is the Application Data Saved?
- Can I Add Yearly/Monthly ECS Instances to an AS Group?
- Can the System Automatically Delete the Instances Added Based on an AS Policy When They Are Not Required?
- What Is the Expected Number of Instances?
- How Do I Delete an ECS Instance Created in a Scaling Action?
- Will a Yearly/Monthly ECS Instance Be Deleted If It Becomes Unhealthy?
- How Do I Handle Unhealthy Instances in an AS Group?
- Why Instances in an AS Group Keep Failing Health Checks and Getting Deleted and Recreated?
- How Do I Prevent Instances from Being Automatically Removed from an AS Group?
- Why Is an Instance that Was Removed from an AS Group and Deleted Still Displayed in the ECS List?
- Do I Need to Bind an EIP to an Instance Before I Manually Add the Instance to an AS Group?
- Can I Apply the Configurations of an Existing Instance in an AS Group to Instances to Be Added in the Future?
- Will the System Bind a New EIP or an Existing One a Newly Added ECS Instance?
-
Others
- How Can I Automatically Deploy My Application on an Instance?
- How Does Cloud-Init Affect the AS Service?
- Why Can't I Use a Key File to Log In to an ECS?
- Do I Need to Configure an EIP in an AS Configuration When a Load Balancer Has Been Enabled for an AS Group?
- How Do I Enable Automatic Initialization of EVS Disks on Instances that Have Been Added to an AS Group During Scaling Actions?
-
General
- Videos
- Glossary
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More Documents
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User Guide (ME-Abu Dhabi Region)
- Service Overview
- Best Practices
- Quick Start
- AS Management
-
FAQs
-
General
- What Are Restrictions on Using AS?
- Are ELB and Cloud Eye Mandatory for AS?
- Is AS Billed?
- Does an Abrupt Change on Monitoring Indicator Values Cause an Incorrect Scaling Action?
- How Many AS Policies and AS Configurations Can I Create and Use?
- Can AS Automatically Scale Up or Down vCPUs, Memory, and Bandwidth of ECSs?
- What Is the AS Quota?
- Why is a message displayed indicating that the key pair does not exist and the operation is discontinued when several users under the same account operate AS resources?
- AS Group
-
AS Policy
- How Many AS Policies Can Be Enabled?
- What Are the Conditions to Trigger an Alarm in the AS Policy?
- What Is a Cooldown Period? Why Is It Required?
- Can AS Scale Capacity Based on Custom Monitoring of Cloud Eye?
- What Will Monitoring Metrics for an AS Group Be Affected If VM Tools Are Not Installed on ECSs?
- What Can I Do If an AS Policy Fails to Be Enabled?
- How Can I Install the Agent Plug-in on the Instances in an AS Group to Use Agent Monitoring Metrics?
-
Instance
- How Do I Prevent Instances Manually Added to an AS Group from Being Removed Automatically?
- What Are the Sequence of Selecting Flavors in Multi-Flavor AS Configuration?
- Will the Application Data on an Instance Be Retained After the Instance Is Removed from an AS Group and Deleted?
- Can I Add ECSs Charged in Yearly/Monthly Mode?
- Can Instances That Have Been Added Based on an AS Policy Be Automatically Deleted When They Are Not Required?
- What Is the Expected Number of Instances?
- How Do I Delete an ECS Created in a Scaling Action?
- Will a Yearly/Monthly ECS Be Deleted When the ECS Becomes Faulty?
- How Should I Handle Abnormal Instances in an AS Group?
- What Can I Do If Instances in an AS Group Frequently Fail in Health Checks and Are Deleted and Then Created Repeatedly?
- How Do I Prevent ECSs from Being Removed from an AS Group Automatically?
- Why Is an Instance Removed and Deleted from an AS Group Still Displayed in the ECS List?
-
Others
- What Can I Do to Enable My Application to Be Automatically Deployed on an Instance?
- How Does Cloud-Init Affect the AS Service?
- How Can I Run Existing Services on an Instance Newly Added to an AS Group?
- Why Cannot I Use a Key File to Log In to an ECS?
- Do I Need to Configure an EIP in an AS Configuration When A Load Balancer Has Been Enabled in an AS Group?
- How Can I Enable Automatic Initialization of EVS Disks of Instances That Have Been Added in a Scaling Action to an AS Group?
-
General
- Change History
-
API Reference (ME-Abu Dhabi Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
API
- AS Groups
- AS Configurations
- Instances in an AS Group
-
AS Policies
- Creating an AS Policy
- Creating an AS Policy (V2)
- Modifying an AS Policy
- Modifying an AS Policy (V2)
- Querying AS Policies
- Querying AS Policies (V2)
- Querying All AS Policies (V2)
- Querying AS Policy Details
- Querying Details of an AS Policy (V2)
- Executing, Enabling, or Disabling an AS Policy
- Deleting an AS Policy
- Performing Operations on AS Policies in Batches
- AS Policy Execution Logs
- Scaling Action Logs
- Quotas
- Notifications
- Lifecycle Hook
- Tag Management
- API Management
- Permissions Policies and Supported Actions
- Appendix
- Change History
-
User Guide (Paris Regions)
- Service Overview
- Best Practices
- Quick Start
- AS Management
-
FAQs
-
General
- What Are Restrictions on Using AS?
- Must I Use AS Together With ELB and Cloud Eye?
- Will an Abrupt Change in Monitoring Metric Values Trigger an Unnecessary Scaling Action?
- How Many AS Policies and AS Configurations Can I Create and Use?
- How Do I Fix the Error "The key pair does not exist" When I Connect to an Instance?
- AS Group
-
AS Policy
- How Many AS Policies Can I Enable?
- What Are the Conditions to Trigger an Alarm-based AS Policy?
- What Is a Cooldown Period and Why Is It Required?
- What Monitoring Metrics for an AS Group Will Be Affected If VM Tools Are Not Installed on the Instances in the Group?
- What Can I Do If an AS Policy Fails to Be Enabled?
-
Instance
- How Do I Prevent Instances Manually Added to an AS Group from Being Automatically Removed?
- When an Instance Is Removed from an AS Group and Deleted, Is the Application Data Saved?
- Can AS Automatically Delete Instances Added Based on an AS Policy When They Are Not Required?
- What Is the Expected Number of Instances?
- How Do I Delete an ECS Instance Created in a Scaling Action?
- How Do I Handle Unhealthy Instances in an AS Group?
- Why Instances in an AS Group Keep Failing Health Checks and Getting Deleted and Recreated?
- How Do I Prevent Instances from Being Automatically Removed from an AS Group?
- Why Is an Instance that Was Removed from an AS Group and Deleted Still Displayed in the ECS List?
-
Others
- How Can I Automatically Deploy My Application on an Instance?
- Why Can't I Use a Key File to Log In to an ECS?
- Do I Need to Configure an EIP in an AS Configuration When a Load Balancer Has Been Enabled for an AS Group?
- How Do I Enable Automatic Initialization of EVS Disks on Instances that Have Been Added to an AS Group During Scaling Actions?
-
General
- Change History
- API Reference (Paris Regions)
-
User Guide (Kuala Lumpur Region)
- Service Overview
- Best Practices
- Quick Start
- AS Management
-
FAQs
-
General
- What Are Restrictions on Using AS?
- Must I Use AS Together With ELB and Cloud Eye?
- Is AS Billed?
- Will an Abrupt Change in Monitoring Metric Values Trigger an Unnecessary Scaling Action?
- How Many AS Policies and AS Configurations Can I Create and Use?
- Can AS Automatically Scale Up or Down vCPUs, Memory, and Bandwidth of ECSs?
- What Is an AS Quota?
- How Do I Fix the Error "The key pair does not exist" When I Connect to an Instance?
- AS Group
-
AS Policy
- How Many AS Policies Can I Enable?
- What Are the Conditions to Trigger an Alarm-based AS Policy?
- What Is a Cooldown Period and Why Is It Required?
- Can AS Scale Capacity Based on Custom Monitoring by Cloud Eye?
- What Monitoring Metrics for an AS Group Will Be Affected If VM Tools Are Not Installed on the Instances in the Group?
- What Can I Do If an AS Policy Fails to Be Enabled?
- How Do I Install the Agent on Instances in an AS Group to Use Agent Monitoring Metrics?
-
Instance
- How Do I Prevent Instances Manually Added to an AS Group from Being Automatically Removed?
- When There Are Multiple Flavors Included in the AS Configuration of an AS Group, What Order Are the Flavors Selected in During Scale-out Events?
- When an Instance Is Removed from an AS Group and Deleted, Is the Application Data Saved?
- Can I Add Yearly/Monthly ECS Instances to an AS Group?
- Can the System Automatically Delete the Instances Added Based on an AS Policy When They Are Not Required?
- What Is the Expected Number of Instances?
- How Do I Delete an ECS Instance Created in a Scaling Action?
- Will a Yearly/Monthly ECS Instance Be Deleted If It Becomes Unhealthy?
- How Do I Handle Unhealthy Instances in an AS Group?
- Why Instances in an AS Group Keep Failing Health Checks and Getting Deleted and Recreated?
- How Do I Prevent Instances from Being Automatically Removed from an AS Group?
- Why Is an Instance that Was Removed from an AS Group and Deleted Still Displayed in the ECS List?
-
Others
- How Can I Automatically Deploy My Application on an Instance?
- How Does Cloud-Init Affect the AS Service?
- Why Can't I Use a Key File to Log In to an ECS?
- Do I Need to Configure an EIP in an AS Configuration When a Load Balancer Has Been Enabled for an AS Group?
- How Do I Enable Automatic Initialization of EVS Disks on Instances that Have Been Added to an AS Group During Scaling Actions?
-
General
- Change History
-
API Reference (Kuala Lumpur Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
APIs
- AS Groups
- AS Configurations
- Instances in an AS Group
-
AS Policies
- Creating an AS Policy
- Creating an AS Policy (V2)
- Modifying an AS Policy
- Modifying an AS Policy (V2)
- Querying AS Policies
- Querying AS Policies (V2)
- Querying All AS Policies (V2)
- Querying AS Policy Details
- Executing, Enabling, or Disabling an AS Policy
- Deleting an AS Policy
- Performing Operations on AS Policies in Batches
- AS Policy Execution Logs
- Scaling Action Logs
- Quotas
- Notifications
- Lifecycle Hook
- Tag Management
- API Management
- Permissions Policies and Supported Actions
- Appendix
- Change History
-
User Guide (Ankara Region)
- Service Overview
- Best Practices
- Quick Start
- AS Management
-
FAQs
-
General
- What Are Restrictions on Using AS?
- Must I Use AS Together With ELB and Cloud Eye?
- Will an Abrupt Change in Monitoring Metric Values Trigger an Unnecessary Scaling Action?
- How Many AS Policies and AS Configurations Can I Create and Use?
- How Do I Fix the Error "The key pair does not exist" When I Connect to an Instance?
- AS Group
-
AS Policy
- How Many AS Policies Can I Enable?
- What Are the Conditions to Trigger an Alarm-based AS Policy?
- What Is a Cooldown Period and Why Is It Required?
- What Monitoring Metrics for an AS Group Will Be Affected If VM Tools Are Not Installed on the Instances in the Group?
- What Can I Do If an AS Policy Fails to Be Enabled?
-
Instance
- How Do I Prevent Instances Manually Added to an AS Group from Being Automatically Removed?
- When an Instance Is Removed from an AS Group and Deleted, Is the Application Data Saved?
- Can AS Automatically Delete Instances Added Based on an AS Policy When They Are Not Required?
- What Is the Expected Number of Instances?
- How Do I Delete an ECS Instance Created in a Scaling Action?
- How Do I Handle Unhealthy Instances in an AS Group?
- Why Instances in an AS Group Keep Failing Health Checks and Getting Deleted and Recreated?
- How Do I Prevent Instances from Being Automatically Removed from an AS Group?
- Why Is an Instance that Was Removed from an AS Group and Deleted Still Displayed in the ECS List?
-
Others
- How Can I Automatically Deploy My Application on an Instance?
- How Does Cloud-Init Affect the AS Service?
- Why Can't I Use a Key File to Log In to an ECS?
- Do I Need to Configure an EIP in an AS Configuration When a Load Balancer Has Been Enabled for an AS Group?
- How Do I Enable Automatic Initialization of EVS Disks on Instances that Have Been Added to an AS Group During Scaling Actions?
-
General
- Change History
-
API Reference (Ankara Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
APIs
- AS Groups
- AS Configurations
- Instances
-
AS Policies
- Creating an AS Policy
- Creating an AS Policy (V2)
- Modifying an AS Policy
- Modifying an AS Policy (V2)
- Querying AS Policies Bound to an AS Group
- Querying AS Policies Bound to a Scaling Resource (V2)
- Querying AS Policies (V2)
- Querying an AS Policy
- Querying an AS Policy (V2)
- Executing, Enabling, or Disabling an AS Policy
- Deleting an AS Policy
- Batch Managing AS Policies
- AS Policy Execution Logs
- Scaling Action Logs
- Quotas
- Notifications
- Lifecycle Hooks
- API Version Query
- Permissions and Supported Actions
- Appendix
- Change History
-
User Guide (ME-Abu Dhabi Region)
- General Reference
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AS Advantages
AS automatically scales resources to keep up with service demands based on pre-configured AS policies. With automatic resource scaling, you can enjoy reduced costs, improved availability, and high fault tolerance. AS is used for the following scenarios:
- Heavy-traffic forums: The traffic on a popular forum is difficult to predict. AS dynamically adjusts the number of ECS instances based on monitored ECS metrics, such as vCPU and memory usage.
- E-commerce: During big promotions, e-commerce websites need more resources. AS automatically increases ECS instances and bandwidths within minutes to ensure that promotions go smoothly.
- Live streaming: A livestreaming website may broadcast popular programs from 14:00 to 16:00 every day. AS automatically scales out ECS and bandwidth resources during this period to ensure a smooth viewer experience.
Automatic Resource Scaling
AS adds ECS instances and increases bandwidths for your applications when the access volume increases and removes unneeded resources when the access volume drops, ensuring system stability and availability.
- Scaling ECS Instances on Demand
AS scales ECS instances for applications based on demand, improving cost management. ECS instances can be scaled dynamically, on a schedule, or manually:
- Dynamic scaling
Dynamic scaling allows scale resources in response to changing demand using alarm-based policies.
- Scheduled scaling
Scheduled scaling helps you set up your scaling schedule according to predictable load changes by creating periodic or scheduled policies.
- Manual scaling
You can either manually change the expected number of instances of your AS group, or add or remove instances to or from the AS group.
Consider a train ticket booking application running on the public cloud. The load of the application may be relatively low during Q2 and Q3 because there are not many travelers, but relatively high during Q1 and Q4. Traditionally, there are two ways to plan for these changes in load. The first option is to provide enough servers so that the application always has enough capacity to meet demand, as shown in Figure 1. The second option is to provision servers according to the average load of the application, as shown in Figure 2. However, these two options may waste resources or be unable to meet demand during peak seasons. By enabling AS for this application, you have a third option available. AS helps you scale servers to keep up with changes in demand. This allows the application to maintain steady, predictable performance without wasting money on any unnecessary resources, as shown in Figure 3.
- Dynamic scaling
- Scaling Bandwidth on Demand
AS adjusts bandwidth for an application based on demand, reducing bandwidth costs.
There are three types of scaling policies you can use to adjust the IP bandwidth on demand:
- Alarm-based policies
You can configure triggers based on metrics such as outbound traffic and bandwidth. When the system detects that the triggering conditions are met, the system automatically adjusts the bandwidth.
- Scheduled policies
The system automatically increases, decreases, or adjusts the bandwidth to a fixed value on a fixed schedule.
- Periodic policies
The system periodically adjusts the bandwidth based on a configured periodic cycle.
For example, you can use an alarm-based policy to regulate the bandwidth for a livestreaming website.
For a livestreaming website, service load is difficult to predict. In this example, the bandwidth needs to be dynamically adjusted between 10 Mbit/s and 30 Mbit/s based on metrics such as outbound traffic and inbound traffic. AS can automatically adjust the bandwidth to meet requirements. You just need to select the relevant EIP and create two alarm policies. One policy is to increase the bandwidth by 2 Mbit/s when the outbound traffic is greater than X bytes, with the limit set to 30 Mbit/s. The other policy is to decrease the bandwidth by 2 Mbit/s when the outbound traffic is less than X bytes, with the limit set to 10 Mbit/s.
- Alarm-based policies
- Evenly Distributing Instances by AZ
To reduce the impact of power or network outage on system stability, AS attempts to distribute ECS instances evenly across the AZs that are used by an AS group.
A region is a geographic area where resources used by ECS instances are located. Each region contains multiple AZs where resources use independent power supplies and networks. AZs are physically isolated from one another but interconnected through an intranet. AZs are engineered to be isolated from failures in other AZs. They provide cost-effective, low-latency network connections to other AZs in the same region.
An AS group can contain ECS instances in one or more AZs within a region. When scaling the capacity of an AS group, AS attempts to evenly distribute ECS instances across AZs used by the AS group based on the following rules:
Evenly distributing new instances to balanced AZs
AS attempts to evenly distribute ECS instances across the AZs used by an AS group. To do it, AS adds new instances to the AZ with the fewest instances.
Consider an AS group containing four instances that are evenly distributed in the two AZs used by the AS group. If a scaling action is triggered to add four more instances to the AS group, AS adds two to each AZ.
Figure 4 Evenly distributing instancesRe-balancing instances across AZs
After you have manually added or removed instances to or from an AS group, the AS group can become unbalanced between AZs. AS compensates by re-balancing the AZs during the next scaling action.
Consider an AS group containing three instances that are distributed in AZ 1 and AZ 2, with two in AZ 1 and one in AZ 2. If a scaling action is triggered to add five more instances to the AS group, AS adds two to AZ 1 and three to AZ 2.
Figure 5 Re-balancing instances
Enhanced Cost Management
AS enables you to use ECS instances and bandwidths on demand by automatically scaling resources for your applications, eliminating waste of resources and reducing costs.
Higher Availability
AS ensures that you always have the right amount of resources available to handle the fluctuating load of your applications.
Using ELB with AS
Working with ELB, AS automatically scales ECS instances based on changes in demand while ensuring that the load of all the instances in an AS group stays balanced.
After ELB is enabled for an AS group, AS automatically associates a load balancing listener with any instances added to the AS group. Then, ELB automatically distributes traffic to all healthy instances in the AS group through the listener, which improves system availability. If the instances in the AS group are running a range of different types of applications, you can bind multiple load balancing listeners to the AS group to listen to each of these applications, improving service scalability.
High Fault Tolerance
AS monitors instances in an AS group, and replaces any unhealthy instances it detects with new ones.
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