FAQs
Last updated:2026-01-06 12:11:46
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-up or scaled-down?
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-up 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-up CPU specifications. After automatic scale-down is enabled or custom scale-up is disabled, the node will automatically scale down 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-up feature is triggered for the primary instance, its mounted read-only instances and disaster recovery instances will not scale up their CPUs simultaneously and require separate enabling of the CPU elastic scale-up 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-up is enabled with the scale-up method set to custom scale-up and the scale-up time set to now, the scale-up will persist until it is manually disabled. After enabling custom scale-up with scale-up time being now, remember to manually disable it based on business needs.
It is recommended that you select automatic scale-up. After selection, elastic scaling on CPU specifications will be automatically performed based on the scaling rules configured by the user. Only when the scale-up is successfully triggered, the cores for scale-up will be charged, and there will be no charge when the scale-up 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-up. If automatic scale-up exceeds 10 minutes, the fees are calculated based on the actual scale-up time; if automatic scale-up lasts 10 minutes or less, the fees are calculated for 10 minutes.
After the CPU Elastic Scale-up Feature Is Enabled, How Do We Determine Whether the Scale-up Has Taken Effect?
You can choose Specification Configurations > Instance Specification on the instance details page to check whether the scale-up has taken effect. If the number of CPU cores shows an additional number (actual number of cores), it indicates that the scale-up has taken effect. As shown in the figure below, 4 (8) cores indicate that the instance has been automatically scaled up to 8 cores.
What Are the Effective Policies for Different Scale-up Methods and Times?
When the scale-up method is automatic scale-up, the instance will be automatically scaled up if the average CPU utilization reaches the set elastic scale-up threshold, and scaled down if the average CPU utilization reaches the set elastic scale-down threshold.
When the scale-up method is custom scale-up with the scale-up time being now, the instance will be scaled up immediately and continue running with the scaled up CPU cores until the feature is manually disabled.
When the scale-up method is custom scale-up with the scale-up time set by period or cycle, if automatic scale-up is not enabled, the instance will be scaled up within the selected period or cycle and scaled down outside the selected period or cycle.
When the scale-up method is custom scale-up with the scale-up time set by period or cycle, if automatic scale-up is enabled, the instance will be scaled up within the selected period or cycle and automatically scaled down/up based on the scaling rules configured for automatic scale-up outside the selected period or cycle.
Why Is Elastic Scale-up 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-up feature again, re-enable it.
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