FAQs
Last updated: 2025-11-13 14:17:44
This document gives FAQs related to the CPU Elastic Scaling feature.
Why can't I find the CPU Elastic Scaling feature in the console?
The CPU Elastic Scaling feature is only available for MySQL Universal Edition with two or three-node instances, or single-node instances with local disks (read-only instance). You can verify whether an instance is a single-node (cloud disk version), dedicated instance, or cluster edition (cloud disk version) instance. The aforementioned types of instances currently do not support the CPU Elastic Scaling feature.
During stress testing, why does the monitoring show that the CPU utilization remains at 100% even after the feature is enabled?
CPU utilization is calculated based on the actual number of CPU cores. If the service load fully utilizes all CPU performance, performance-related metrics such as TPS, QPS, and response time of the database system should be given attention.
Why does the CPU Elastic Scaling feature fail to be enabled?
There are two possible reasons for the failure to enable the CPU elastic scaling feature:
Your Tencent Cloud account does not have a sufficient balance.
The CPU resources on the host is insufficient (rarely occurs).
Why am I not notified of events when the CPU is scaled-out or scaled-in?
You can troubleshoot and handle the issue as follows.
Check whether the alarm for CPU elastic scaling events has been enabled. If not, enable it by referring to Enabling Event Alarms.
Check the notification recipient list; it is possible that no relevant users have been added. You can add the notification recipient by referring to Adding Message Recipients.
What should I do if a HA switch occurs after the CPU Elastic Scaling feature is enabled?
The CPU elastic scale-out feature for two-node and three-node instances takes effect on both the source node and the replica node simultaneously. If an HA switch for two-node and three-node instances occurs after the feature takes effect, the switched node will also inherit the scaled-out CPU specifications. After automatic scale-in is enabled or custom scale-out is disabled, the node will automatically scale in to the original CPU specification. Note: Read-only instances and disaster recovery instances require separate enabling of the feature and do not scale out simultaneously. Once the CPU elastic scale-out feature is triggered for the primary instance, its mounted read-only instances and disaster recovery instances will not scale out their CPUs simultaneously and require separate enabling of the CPU elastic scale-out feature.
How can I query the progress and details related to CPU elastic scaling tasks?
You can query the progress and details related to CPU elastic scaling tasks through the task list, with the following steps:
1. Log in to the TencentDB for MySQL console.
2. Choose Task List on the left sidebar, select the region, click Task Type, choose Configure Elastic Expansion Strategy, and then click OK.
3. In the filtered task list, locate the target task to inquire about its progress. Click Task Details in the operation column to view detailed task information.
Why am I continuously billed after the CPU Elastic Scaling feature is enabled?
If CPU elastic scale-out is enabled with the scale-out method set to custom scale-out and the scale-out time set to now, the scale-out will persist until it is manually disabled. After enabling custom scale-out with scale-out time being now, remember to manually disable it based on business needs.
It is recommended that you select automatic scale-out. After selection, elastic scaling on CPU specifications will be automatically performed based on the scaling rules configured by the user. Only when the scale-out is successfully triggered, the cores for scale-out will be charged, and there will be no charge when the scale-out is not performed.
Within one hour after automatic scaling is enabled, it automatically scales in only 6 minutes after scaling was triggered. Why am I being charged for 10 minutes?
To avoid the impact of continuous intermittent peaks, a minimum protection period of 10 minutes applies during automatic scale-out. If automatic scale-out exceeds 10 minutes, the fees are calculated based on the actual scale-out time; if automatic scale-out lasts 10 minutes or less, the fees are calculated for 10 minutes.
After the CPU Elastic Scale-out Feature Is Enabled, How Do We Determine Whether the Scale-out Has Taken Effect?
You can check whether it has taken effect in Instance Configuration on the instance details page. If the (actual number of cores) is also displayed after the number of CPU cores, it indicates that it has taken effect. As shown in the figure below, 4 (8) cores indicates that the current number of cores has been scaled out to 8.
What Are the Effective Policies for Different Scale-out Methods and Times?
When the scale-out method is automatic scale-out, the instance will be automatically scaled out if the average CPU utilization reaches the set elastic scale-out threshold, and scaled in if the average CPU utilization reaches the set elastic scale-in threshold.
When the scale-out method is custom scale-out with the scale-out time being now, the instance will be scaled out immediately and continue running with the scaled out CPU cores until the feature is manually disabled.
When the scale-out method is custom scale-out with the scale-out time set by period or cycle, if automatic scale-out is not enabled, the instance will be scaled out within the selected period or cycle and scaled in outside the selected period or cycle.
When the scale-out method is custom scale-out with the scale-out time set by period or cycle, if automatic scale-out is enabled, the instance will be scaled out within the selected period or cycle and automatically scaled in/out based on the scaling rules configured for automatic scale-out outside the selected period or cycle.
Why Is Elastic Scale-out Automatically Disabled After Being Enabled for a Period of Time?
After an instance is upgraded or migrated, the elastic feature will be automatically disabled due to changes in underlying machine resources. If you want to use the CPU elastic scale-out feature again, re-enable it.
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