Adjusting Database Instance Specifications
TencentDB for MySQL supports quick adjustment of instance specifications through the Console, offering flexible scaling operations. You can dynamically adjust MySQL instance specifications based on actual business phases (initial phase, rapid growth period, peak hours, off-peak seasons, and so on) to better meet requirements for resource utilization and real-time cost optimization.
For cloud disk edition instances, you can also add or delete read-only nodes and modify node AZs during the configuration adjustment operation. See Adjusting Instance Configurations.
Instance Disk Over Quota Notes
To ensure the normal operation of your business, when the disk space is almost full, please promptly upgrade the database instance specifications or purchase additional disk space.
Notes:
Disk space can be viewed on the MySQL Console instance details page. You can also receive hard disk alarm messages in a timely manner by configuring alarms.
When the data storage of an instance exceeds its current storage space, the instance will be locked, allowing only read operations and no write operations. You need to scale out or delete some database tables in the console to remove the read-only state. If your instance is a single-node architecture, you can only remove the read-only state by scaling out.
To avoid repeated triggering of the locked state for the database, the locked state will be lifted and normal read and write feature will be resumed only when the remaining space of the instance is greater than 20% or 50 GB.
Configuration Adjustment Introduction
After a user changes the instance configuration in the console, the system will complete the change through data migration. By default, it is a normal configuration adjustment. If local (that is, the host where the instance resides) resources are sufficient, you can also choose rapid configuration adjustment. The configuration adjustment process is as follows:
Normal mode: It is completed by migrating instance data from the current host to a new host. During this process, data migration, comparison, and verification are required. When the data volume is large, the overall configuration adjustment takes longer, and upon completion, an instance switch may be involved.
QuickChange mode: The overall configuration adjustment process takes less time. Whether primary/secondary switching is involved is subject to the actual prompts on the configuration adjustment page. Currently, it is divided into the following scenarios.
Disk Type | Adjustment Item | Adjustment Impact |
Local Disk | Instance compute specification change only or combined configuration adjustment (specification upgrade/downgrade + disk scaling) | When local resources are sufficient and the parameters involved in the parameter change do not require a restart, the current change does not involve primary/secondary switching or a restart. The configuration adjustment page will display the message: "This change does not involve data migration or instance restart." |
| | When local resources are sufficient but the parameters involved in the parameter change require a restart, the current change involves primary/secondary switching and a restart. The configuration adjustment page will display the message: "Instance access is not affected during the configuration adjustment. After preparation is complete, a switch will be performed, which may cause a second-level momentary disconnection. Ensure that your business has a reconnection mechanism." |
| | When local resources do not meet the requirements for configuration adjustment, the current change involves primary/secondary switching and a restart. The configuration adjustment page will display the message: "Instance access is not affected during the configuration adjustment. After preparation is complete, a switch will be performed, which may cause a second-level momentary disconnection. Ensure that your business has a reconnection mechanism." |
| Disk scaling | When only the disk capacity is changed, primary/secondary switching and a restart are not involved. The configuration adjustment page will display the message: "This change does not involve data migration or instance restart." |
Note:
Whether instance configuration adjustment can trigger rapid configuration adjustment is closely related to the host machine's resource status. Please refer to whether the rapid configuration adjustment switch is activated on the actual configuration adjustment page.
If the rapid configuration adjustment switch is activated, it indicates that the current host machine has sufficient resources to support rapid configuration adjustment.
If the rapid configuration adjustment switch is not activated, it indicates insufficient host machine resources, and rapid configuration adjustment cannot be performed.
When sufficient local resources are available to meet the requirements for rapid configuration adjustment, the rapid configuration adjustment capability is enabled by default. If you do not need to use this capability, disable it on the configuration adjustment page. (You can choose to enable or disable the "Rapid Configuration Adjustment" button on the configuration adjustment page).
Instances deployed across multiple AZs do not support rapid configuration adjustment.
Precautions
When the RO instance has independent VIP access enabled, it does not support rapid configuration adjustment.
When the number of active instances in the RO group where the RO instance resides is ≤ the minimum number of instances for delayed removal, the RO instance does not support rapid configuration adjustment.
When minor versions are upgraded, whether a restart is involved depends on the prompt on the configuration adjustment page.
Adjust configuration rules
Adjust configuration rules
A configuration adjustment operation can only be initiated when the TencentDB for MySQL instance and its associated read-only instances and disaster recovery instances are in a normal state (Running) and when there are no ongoing tasks.
During the configuration adjustment process, it is not allowed to cancel this configuration adjustment operation.
The name, access IP, and access port of the instance remain unchanged before and after the configuration adjustment.
During the configuration adjustment process, please avoid modifying MySQL global parameters, user passwords, and other operations.
During the configuration adjustment process, data migration may be involved. The MySQL instance remains accessible during this period without service interruption.
When the configuration adjustment is completed, an instance switchover may be involved (that is, a second-level MySQL database disconnection). It is recommended that applications be equipped with an automatic reconnection feature and that the switchover is performed during the instance maintenance window. See Setting Instance Maintenance Time.
MySQL single-node - basic instances will experience approximately 15 minutes of unavailability during configuration adjustment. It is recommended to perform this operation during off-peak hours.
Instance Specifications and Storage Tables
For information about instance specifications and storage tables, see Database Instance Specifications.
Notes:
The maximum storage space for instance specifications may vary across different regions. Please refer to the actual purchase page for details.
Adjust Instance Configuration via the Console
1. Log in to the MySQL Console, select the target instance in the instance list, and choose More > Adjust Configurations in the Operation column.
2. In the pop-up dialog box, select the adjusted configuration and click Submit.
Notes:
When local remaining resources are sufficient, the rapid configuration adjustment capability will be triggered, meaning the QuickChange button on this page will take effect, allowing users to choose to enable or disable it.
When you only need to adjust the hard disk (storage space), no restart is involved. If you enable the extreme speed configuration adjustment, the system will provide options for execution time.
In some rapid configuration adjustment scenarios, no restart is involved. In such cases, the submitted configuration adjustment takes effect immediately upon completion. As shown in the figure below:
When the primary instance triggers migration and configuration adjustment, the data validation sensitivity setting will be presented. You can configure the data validation speed using high, standard, or low modes based on actual requirements.
High: When the database load pressure increases, the data consistency comparison task will be suspended to avoid additional performance impact, which will prolong the duration of the data consistency comparison task.
Standard: When the database load pressure is high, the data consistency comparison task will be suspended to avoid significant performance impact caused by the task.
Low: When the database load pressure is high, the data consistency comparison task will continue to execute to shorten the duration of the task.
If the CPU elastic scale-out feature is enabled for an instance and you need to perform the configuration adjustment operation, note that the CPU elastic scale-out feature will become invalid after the configuration adjustment is completed. Check whether the adjusted CPU meets business needs promptly. If you want to use the CPU elastic scale-out feature again, re-enable it.
Adjust Instance Configuration via API
Users can use the UpgradeDBInstance API to adjust instance configurations. See Adjusting Cloud Database Instance Configurations.
FAQs
During Configuration Adjustment, Will Primary/Standby Delay Occur?
The configuration adjustment process for the primary instance involves data comparison, which may cause primary/standby delay.
What Are the Effects of Adjusting Database Instance Specifications?
During the MySQL configuration adjustment process, data migration may occur. Instance access remains unaffected during migration; however, a brief disconnection of several seconds may occur during the switchover upon completion. Ensure that your business has a reconnection mechanism.
MySQL single-node - basic instances will experience approximately 15 minutes of unavailability during configuration adjustment. It is recommended to perform this operation during off-peak hours.
Why Can't My Database Be Downgraded in Configuration?
It is possible that your storage has exceeded the maximum disk capacity. You need to clean up data first to ensure the remaining free space is greater than 20% or 50GB before performing the downgrade operation.
Why Does the Console Display "Upgrade Pending Switch" Status After Configuration Adjustment?
It is possible that when you adjusted the configuration in the console, you selected switch within the maintenance window for the switch time, preventing immediate switching.
If you need to switch immediately, click Switch Now in the Operation column of the instance list. Note that the switch will cause a momentary disconnection lasting seconds. Ensure your service has a reconnection mechanism.
How Long Does It Take to Adjust Instance Specifications and Perform the Upgrade?
The database upgrade time depends on the data volume in your current database and the data replication speed, and the specific duration cannot be estimated.
The upgrade process will not affect the normal use of your current instance. A momentary disconnection lasting seconds may occur during VIP switchover upon completion.
Where Can I View the Instance Adjustment Progress?
Hard Drive Space Is About to Run Out, What Should I Do?
When user disk space usage has reached or exceeded 85%, it is recommended to delete unnecessary data or scale out disk space. Disk space scaling can be performed via the console (choose More > Adjust Configuration in the Operation column on the right side of the instance list).
How to Confirm Whether My Instance Supports Rapid Configuration Adjustment for Memory Expansion (Disk Scaling)
On the configuration adjustment page, you can determine whether the rapid configuration adjustment capability can be used by checking the switch status. When not needed, you can manually disable it. This capability cannot be enabled if the requirements for rapid configuration adjustment are not met.
Whether Scaling Out Memory or Disk Affects the Minor Version of the Instance
When the instance minor version is not the latest, the kernel minor version will be upgraded to the newest. During minor version upgrades, the rapid configuration adjustment capability will restart the database.
Will Rapid Configuration Adjustment Restart the Instance?
During configuration adjustment, the instance may be restarted in specific scenarios. Whether a restart is involved will be indicated in the note at the bottom of the configuration adjustment page, as shown below:
Notes:
Only disk configuration adjustment will not trigger a restart under the condition that the instance minor version is the latest and the rapid configuration adjustment capability is activated.
How to Determine Whether It Is Rapid Configuration Adjustment When an Upgrade Is Performed in the Console?
You can determine by checking whether the Rapid Configuration Adjustment button is enabled on the configuration adjustment page.
How to Determine Whether It Is Rapid Configuration Adjustment When Changing Configurations via API?
The API currently only supports configuration adjustment and upgrade through the migration approach and cannot provide rapid configuration adjustment specifications. API support will be provided in the future.
Will Database Parameters Be Adjusted During Configuration Adjustment?
The innodb_buffer_pool_size parameter will be adjusted to accommodate configuration changes.
Will Parameters Be Adjusted After Rapid Configuration Adjustment Is Triggered During Database Configuration Adjustment?
Similar to regular configuration adjustments, parameters will be adjusted accordingly to changes in instance specifications.
What Are the Differences Between Rapid Configuration Adjustment Versus Regular Configuration Adjustment?
Rapid configuration adjustment reduces the time required for data migration.
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