Configuring auto scale-out
Last updated:2026-01-06 12:11:46
This document introduces operations related to setting automatic expansion.
Prerequisites
The instance architecture is TencentDB for MySQL general edition two-node, general edition three-node, and single-node local disk (read-only instance).
The instance specification is equal to or less than 32 cores before the CPU Elastic Scaling feature is enabled.
Your Tencent Cloud account has sufficient balance.
The underlying machine supports scale-up. If scale-up is not supported for the underlying machine, the operation of setting automatic expansion will fail.
Billing Instructions
Enabling Automatic Scaling
Note：
After automatic expansion is enabled, there is a very low probability that the feature will fail to be triggered. The backend will retry multiple times until the operation is successful.
1. Log in to the TencentDB for MySQL console. In the instance list, click an Instance ID or Manage in the Operation column to go to the instance details page.
2. Choose Instance Details > Specification Configurations > Elastic CPU Expansion, and click Enable.
3. In the Elastic CPU Expansion window, complete the following settings, and after confirming the scaling fee, click Expand Now.
Parameter | Description |
Scale-Up Method | Automatic Expansion and Custom Scale-up are supported. Select automatic expansion here. Automatic Expansion: Perform quick elastic scale-up according to performance to handle traffic peaks, and perform scale-down when traffic drops. Custom Scale-up: You can select a period for scale-up and decide whether to enable automatic expansion within other periods. |
Number of Cores for Scale-Up | The default value is consistent with the number of CPU cores of the current instance specification. For example, if the current instance specification is 6-core and 24,000 MB of memory, the number of cores for scale-up will also be 6 cores. After scale-up is successfully triggered, the CPU of the instance will be 12 cores. |
Increased IOPS | By default, the IOPS increases by 1000 for each core scaled up. |
Scale-Up Rule | Set the observation period and threshold for triggering scale-up. Observation period: Supported options include 15 seconds, 30 seconds, 45 seconds, 1 minute, 3 minutes, 5 minutes, 10 minutes, 15 minutes, and 30 minutes. Threshold: Supported options include 40%, 50%, 60%, 70%, 80%, and 90%. |
Scale-Down Rule | Set the observation period and threshold for triggering scale-down. Observation period: Supported options include 5 minutes, 10 minutes, 15 minutes, and 30 minutes. Threshold: Supported options include 10%, 20%, and 30%. |
4. After you enable automatic expansion, you can view the scale-up rules in the Elastic CPU Expansion preview window.
Modifying the Elastic Scale-up Policy for CPU
After automatic expansion is enabled, only scaling rules can be modified under the feature. You can choose Instance Details > Specification Configurations > Elastic CPU Expansion and click Edit for reconfiguration.
After automatic expansion is enabled, it is not supported to directly change the scale-up method (from automatic expansion to custom scale-up) through Edit operation. If changes are needed, disable automatic expansion first, and then adjust the method while re-enabling CPU elastic scale-up.
Disabling Automatic Expansion
Note：
After automatic expansion is disabled, the CPU cores after scale-up will be immediately scaled down to the number before instance scale-up. After scale-down, scale-up will not be performed based on the scale-up threshold.
1. Log in to the TencentDB for MySQL console. In the instance list, click an Instance ID or Manage in the operations column to go to the instance details page.
2. Choose Instance Details > Specification Configurations > Elastic CPU Expansion, and click Disable Scale-Out.
3. In the pop-up window Disable CPU Expansion, click OK.
FAQs
How to Determine If Automatic Expansion Is Effective After the Automatic Expansion Feature Is Enabled for Elastic CPU Expansion?
When the average CPU utilization of an instance reaches the threshold set for automatic elastic scale-up, the instance will be scaled up automatically. You can check whether the scale-up has taken effect by viewing the instance specification on the instance details page. If the number of CPU cores shows an additional number (actual number of cores), it indicates that scale-up has taken effect. For example, if an instance is configured with 4 cores and 8,000 MB of memory, when the configuration displays as 4 cores and 8,000 MB, it indicates that automatic scale-up has not been triggered. When the configuration displays as 4 (8) cores and 8,000 MB, it indicates that the number has been scaled up to 8 cores.
Related APIs
API | Description |
This API is used to enable the Elastic CPU Expansion feature for instances. | |
This API is used to disable the Elastic CPU Expansion feature for instances. |
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