Scenarios

If you have special requirements on the ECSs for resource expansion, use a new specifications template to create the AS configuration. In such a case, ECSs meeting specifications of the template will be added to the AS group in scaling actions.

Procedure

1. Log in to the management console.
2. Under Computing, click Auto Scaling. In the navigation pane on the left, choose Instance Scaling.
3. Click Create AS Configuration.
4. Set the parameters for the AS configuration. Table 1 lists the AS configuration parameters.

   Table 1 AS configuration parameters

   Parameter	Description	Example Value
   Billing Mode	Specifies the billing mode of selected flavors in AS configuration. Pay-per-use and spot price are options. Pay-per-use: a postpaid billing mode, in which an ECS is billed based on service duration. You can create or delete such an ECS at any time. Spot price: a postpaid billing mode, in which a spot ECS is billed based on the service duration at a lower price than that of a pay-per-use ECS with the same specifications. HUAWEI CLOUD offers spot ECSs based on market transaction prices or changes in supply and demand. For more information, see Notes on Spot Price.	Spot price
   Region	A region is where an AS configuration resides.	N/A
   Name	Specifies the name of the AS configuration to be created.	N/A
   Configuration Template	Select Create a new specifications template. If this option is selected, configure parameters, such as the vCPUs, memory, image, disk, and ECS type, to create a new AS configuration.	Create a new specifications template
   CPU Architecture	The following two types of CPU architectures are available: x86: The x86-based CPU architecture uses Complex Instruction Set Computing (CISC). Kunpeng: The Kunpeng-based CPU architecture uses Reduced Instruction Set Computing (RISC).	x86
   DeH	(Optional) Instances automatically created for the AS group run on a DeH. You can choose to allow the system to select a DeH or specify a DeH. If you allow the system to select a DeH, the system will automatically create ECSs on the DeH with the maximum available memory size among all the DeHs that meet the specifications requirements, thereby balancing the load of the DeHs. If you specify a DeH, the system will automatically create ECSs on the DeH you specify. NOTE: This parameter is available only if you have DeHs.	Auto placement
   Specifications	The public cloud provides various ECS types for different application scenarios. For more information, see Elastic Cloud Server User Guide.	Memory-optimized ECS
   Image	Public image A public image is a standard, widely used image. It contains an OS and preinstalled public applications and is available to all users. You can configure the applications or software in the public image as needed. Private image A private image is an image available only to the user who created it. It contains an OS, preinstalled public applications, and the user's private applications. Using a private image to create ECSs removes the need to configure multiple ECSs repeatedly. Shared image A shared image is a private image shared by another public cloud user.	Public image
   Disk	Includes system disks and data disks. System Disk Common I/O: uses Serial Advanced Technology Attachment (SATA) drives to store data. High I/O: uses serial attached SCSI (SAS) drives to store data. Ultra-high I/O: uses solid state disk (SSD) drives to store data. If a full-ECS image is used, the system disk is restored using the disk backup. On the console, you can only change the volume type and size. In addition, the volume cannot be smaller than the disk backup. Data Disk You can create multiple data disks for an ECS. In addition, you can specify a data disk image for exporting data. If the image you selected is of the full-ECS image type, you can change the volume type and size and encryption attributes of the data disk restored using the disk backup. Ensure that the volume size is greater than or equal to the disk backup size, and the encryption attributes can be modified only if the disk backup of the full-ECS image locates in the target region.	Common I/O for System Disk
   Security Group	Controls ECS access within or between security groups by defining access rules. ECSs added to a security group are protected by the access rules you define.	N/A
   EIP	An EIP is a static public IP address bound to an ECS in a VPC. Using the EIP, the ECS provides services externally. The following options are provided: Do not use An ECS without an EIP cannot access the Internet. However, it can still be used as a service ECS or deployed in a cluster on a private network. Automatically assign An EIP with a dedicated bandwidth is automatically assigned to each ECS. You can set the bandwidth size. NOTE: If you select Automatically assign, you need to specify Type, Billed By, and Bandwidth.	Automatically assign
   Bandwidth	You can select Dedicated or Shared. Dedicated: The bandwidth can be used by only one EIP. Shared: The bandwidth can be used by multiple EIPs. NOTE: This parameter is available only when EIP is set to Automatically assign. If you select Dedicated, you can select Bandwidth or Traffic for Billed By. The shared bandwidth can be billed only by bandwidth. You can select a shared bandwidth to which the EIP is to be added.	Shared
   Login Mode	An ECS can be authorized using a key pair or a password. Key pair In this mode, keys are used for authenticating the users who attempt to log in to target ECSs. If you select this mode, create or import a key pair on the Key Pair page. NOTE: If you use an existing key, make sure that you have saved the key file locally. Otherwise, logging in to the ECS will fail. Password In this mode, the initial password of user root (for Linux) or user Administrator (for Windows) is used for authentication. You can log in to an ECS using the username and its initial password.	Admin@123
   Advanced Settings	This parameter allows you to configure File Injection, User Data Injection, and ECS Group. You can select Do not configure or Configure now.	N/A
   File Injection	Enables the ECS to automatically inject a script file or other files into a specified directory on an ECS when you create the ECS. This configuration is optional. For Linux, specify the path for storing the injected file, for example /etc/foo.txt. For Windows, the injected file is automatically stored in the root directory of disk C. You only need to specify the file name, such as foo. The file name can contain only letters and digits. For details, see Injecting Files into ECSs.	N/A
   User Data Injection	Enables the ECS to automatically inject user data when the ECS starts for the first time. This configuration is optional. After this function is enabled, the ECS automatically injects user data upon its first startup. For details, see Elastic Cloud Server User Guide. The following methods are available: As text: allows you to enter the user data in the text box below. As file: allows you to inject script files or other files when you create an ECS. If you select As file, the system automatically injects the files into a specified directory when creating an ECS. For Linux, specify the path for storing the injected file, for example /etc/foo.txt. For Windows, the injected file is automatically stored in the root directory of disk C. You only need to specify the file name, such as foo. The file name can contain only letters and digits. NOTE: For Linux, if you use the password authentication mode, the user data injection function is unavailable. If the selected image does not support user data injection, the user data injection function is unavailable.	-
   ECS Group	An ECS group allows you to create ECSs on different hosts, thereby improving service reliability.	N/A

5. Click Create Now. The system displays a message indicating that the AS configuration is successfully created.
6. If you want to use the newly created AS configuration, add it to the AS group. For details, see Replacing AS Configuration in an AS Group.

Notes on Spot Price

A spot ECS is billed based on the service duration at a low price, which can help you reduce costs.

During the AS group expansion, you are billed the market price of the selected flavors after the use. When the market price is lower than the upper limit you allow to pay (the current price is the same as pay-per-use price) and ECSs of this flavor are sufficient, you can continue using them. If ECSs of this flavor are insufficient, they will be removed by the AS group. Remember to back up your data. For more information about spot ECSs, see Spot ECSs.

• If the flavor price is not registered in the selected AZs and spot price is selected, an AS group exception will occur. When selecting the spot price, ensure that at least one of the selected AZs has a flavor price registered.
• Spot ECSs are applicable to short-term operations and services that do not require high stability, such as image rendering, stateless web services, and gene sequencing. Do not select the spot ECSs for services requiring long-term operations or high stability.

Notes on Multiple Flavors in an AS Configuration

AS configuration supports multiple flavors to minimize the probability of capacity expansion failures due to insufficient or unavailable flavors and ensure that capacity expansion succeeds during peak hours.

Applicable Scenario

• No special requirement for the instance flavors created in the AS group
• Requiring higher success ratio and low latency of creating instances in an AS group
• Requiring instances with high specifications
• Services that are stateless and can be horizontally scaled

The AS group sorts multiple flavors in either of the following ways:

• Sequenced: During AS group expansion, flavors are used based on the sequence they are selected. When the first flavor is insufficient or the instance fails to be created due to other reasons, the system attempts to create an instance of the second flavor, and so on.
• Cost-center: During AS group expansion, the flavor with the minimum cost comes first. When creating an instance in an AS group, the system selects the flavor with the minimum cost. If the instance cannot be created, the system selects one with the minimum cost from the remained flavors, and so on.