TencentDB for MySQL supports flexible scaling that allows you to quickly adjust instance specification in the console. You can do so at any time (at the start, during rapid development, or during peak/off-peak hours), so you can get the most out of your resources and reduce unnecessary costs in real time. For more information, see Instance Adjustment Fee.
In cluster edition instances, the adjustment configuration operation also allows for adding or deleting read-only nodes, change of node availability zones, etc. Please see Adjust Instance Configuration.
Instance Disk Space Description
To ensure business continuity, upgrade your instance specifications or purchase additional disk capacity in time before disk capacity is used up.
Note:
The disk space can be viewed on the instance details page of the MySQL console. You can also configure alarms to receive disk space alarm messages in time.
When the amount of data stored in an instance exceeds the current storage space of the instance, the instance will be locked and become read-only, and you will not be able to write data to it. You need to expand the capacity or delete some database tables in the console to unlock it.
To avoid the database from triggering the lock status repeatedly, a locked instance will be unlocked and allowed for reads and writes only when its remaining available capacity is more than 20% of its total capacity or over 50 GB.
Configuration Adjustment Description
By default, the instance configuration is adjusted in the normal mode, which requires a data migration for the adjustment to complete after you adjust the instance configuration in the console. But if the physical machine where the instance is located has sufficient remaining resources (aka local resources), you can choose the QuickChange mode. The adjustment process is as follows:
Normal mode: to adjust the instance configuration, instance data needs to be migrated from the original physical machine to a new one. Because adjustment in this mode requires data migration, comparison, and verification, the overall adjustment process will take a long time in case of a huge amount of data. Besides, an instance switch may occur after the adjustment is completed.
QuickChange mode: Overall configuration adjustment takes a short time. Whether it involves primary-secondary switching depends on the actual configuration adjustment page reminder. Currently, there are two scenarios as follows.
Scenario 1: The message "The current change will not involve data migration and instance restart" is displayed, indicating that the current change does not involve primary-secondary switching.
Scenario 2: The message "Instance access will not be affected during configuration adjustment; switching will occur after preparation is completed, and there will be a second-level interruption. Please ensure that your business has a reconnection mechanism" is displayed, indicating that the current change involves primary-secondary switching.
Note:
The ability to trigger a rapid configuration change during instance configuration change is closely related to the resource availability of the host machine. Please take the activation status of the rapid configuration change switch on the actual configuration adjustment page as the criterion.
If the Rapid Allocation Switch is activated, it means that the current host resources are sufficient to support rapid configuration changes.
If the rapid configuration change switch is not activated, it means that the host machine lacks sufficient resources to perform rapid configuration change.
When local remaining resources are sufficient to meet the conditions for rapid configuration change, the rapid configuration change will be used by default. If not to use it, turn it off on the Configuration Adjustment page. (i.e. you can choose to enable or disable the "Rapid Configuration Change" button on the Configuration Adjustment Page).
Use Limits
A read-only instance with an exclusive VIP enabled does not support QuickChange.
If a read-only instance group (RO group) enables the "Remove Delayed RO Instances" feature, read-only instances whose delay exceeds the specified threshold will be removed from the RO group until the number of remaining ones reaches the allowed minimum number. If the number of the remaining available read-only instances in an RO group is less than or equal to the allowed minimum number, none of those instances will support QuickChange.
If an RO group only has one read-only instance, the instance does not support QuickChange.
When upgrading a minor version, whether a restart is involved, the prompts on the configuration change page shall prevail.
Configuration Adjustment Rules
You can adjust the configuration of a TencentDB for MySQL instance and its associated read-only and disaster recovery instances only when they are in normal status (running) and are not executing any task.
You cannot cancel a configuration adjustment operation in progress.
The name, access IP, and access port of the instance remain unchanged after configuration adjustment.
During configuration adjustment, you should try to avoid such operations as modifying MySQL's global parameters and user password.
Data migration may be involved in configuration adjustment. During data migration, the TencentDB for MySQL instance can be accessed normally and the business will not be affected.
Instance switchover may be needed after configuration adjustment is completed (i.e., the MySQL instance may be disconnected for seconds). It is recommended that applications be configured with auto reconnection feature and that instance switchover be conducted during the instance maintenance period. For more information, see Setting Instance Maintenance Window.
Basic single-node TencentDB for MySQL instances are unavailable for about 15 minutes in the process of configuration adjustment. We recommend you adjust instance configuration during off-peak hours.
Instance Specification and Storage Table
Two-node/Three-node (local SSD disk)
Isolation Policy
CPU and Memory
Maximum IOPS
Storage Space
General
1-core 1000 MB
1200
25GB - 3000GB
1-core 2000 MB
2000
2-core 4000 MB
4000
4-core 8000 MB
8000
4-core 16000 MB
14000
25GB - 4000GB
8-core 16000 MB
20000
8-core 32000 MB
28000
16-core 32000 MB
32000
16-core 64000 MB
40000
16-core 96000 MB
40000
16-core 128000 MB
40000
25GB - 8000GB
24-core 192000 MB
60000
25GB - 6000GB
24-core 244000 MB
60000
25GB - 8000GB
32-core 256000 MB
80000
48-core 488000 MB
120000
25GB - 12000GB
80-core 690000 MB
140000
Dedicated
2-core 16000 MB
8000
25GB - 4000GB
4-core 16000 MB
10000
4-core 24000 MB
13000
4-core 32000 MB
16000
8-core 32000 MB
32000
8-core 48000 MB
36000
8-core 64000 MB
40000
12-core 48000 MB
36000
25GB - 8000GB
12-core 72000 MB
40000
12-core 96000 MB
48000
16-core 64000 MB
60000
16-core 96000 MB
60000
16-core 128000 MB
60000
24-core 96000 MB
72000
24-core 144000 MB
76000
24-core 192000 MB
80000
32-core 128000 MB
80000
32-core 192000 MB
90000
32-core 256000 MB
100000
48-core 192000 MB
120000
25GB - 10000GB
48-core 288000 MB
140000
48-core 384000 MB
140000
64-core 256000 MB
150000
64-core 384000 MB
150000
64-core 512000 MB
150000
25GB - 12000GB
90-core 720000 MB
150000
Note:
The storage space cap of an instance specification may vary by region as displayed on the purchase page.
Adjusting Instance Configuration in the Console
1. Log in to the TencentDB for MySQL console, locate the desired instance in the instance list, and select More > Adjust Configurations in the Operation column.
2. In the pop-up window, select the desired configuration and click Submit.
Note:
When the local resources are sufficient, you can enable the QuickChange mode by turning on the QuickChange toggle on the configuration adjustment page in the console.
When you are only adjusting the cloud disk (storage space), which does not involve a restart, the system will provide options for the execution time if rapid configuration change is enabled.
In some cases, instance restart is not required in the QuickChange mode and the configuration adjustment will take effect immediately after you submit the request, as shown below:
When the primary instance triggers migration configuration change, the data validation sensitivity settings will be displayed, and you can set the data validation speed to high, standard, or low.
High: Suspends the data consistency comparison task when database load pressure increases, to avoid additional performance impact from the task, which will extend the duration of the data consistency comparison task.
Standard: Suspends the data consistency comparison task when the database load pressure is significant, to prevent noticeable performance impact.
Low: Perform the data consistency comparison task even when the database load pressure is significant, to shorten the duration of the task.
Adjusting Instance Configuration Through API
You can adjust the instance configuration using the UpgradeDBInstance API. For more information, see UpgradeDBInstance.
FAQs
Will there be a primary-secondary delay issue during the configuration change?
During the configuration change of the primary instance, data comparison occurs, which might lead to primary-secondary delay.
Will instance configuration adjustment affect instances?
In the process of TencentDB for MySQL configuration adjustment, data migration may occur, and instances can still be accessed during the process. After the migration is completed, there is a switch which causes a short disconnection lasting for just seconds, ensure that your business has a reconnection mechanism.
Basic single-node TencentDB for MySQL instances are unavailable for about 15 minutes in the process of configuration adjustment. We recommend you adjust instance configuration during off-peak hours.
Why can't my instance be downgraded?
It may be because the used storage capacity has reached the maximum capacity of the hard disk. To downgrade you instance, you need to clean up data first and make sure the remaining available capacity accounts for more than 20% of the total capacity or over 50 GB.
Why is my instance in the "Waiting for switch" status for a long time after I adjust instance configuration in the console?
It may be because you select During maintenance time as the Switch Time when you adjust instance configuration in the console, so the instance will not be switched immediately after the adjustment.
To switch immediately, find the target instance in the instance list and click Switch Now in the Operation column. The switch will cause a momentary disconnection. Make sure that your business has a reconnection mechanism.
How long does it take to upgrade instance configuration?
The time it takes depends on the instance's data volume and data replication speed.
Instances can still be accessed during the upgrade, but after the upgrade is completed, there is a VIP switch which causes a short disconnection lasting for just seconds.
How do I view the progress of instance configuration adjustment?
You can view the progress in Task List in the console.
What should I do if the disk space is being used up?
If over 85% disk space is used, we recommend that you delete data no longer used or expand disk space in the console by selecting More > Adjust Configurations in the Operation column on the right of the instance list.
How do I know whether the QuickChange mode is supported when I adjust instance memory or disk capacity?
On the configuration adjustment page, if the QuickChange mode is supported, the QuickChange toggle can be turned on or off as needed; otherwise, the toggle cannot be used.
Does expanding memory or disk capacity affect the kernel minor version of the instance?
If the kernel minor version of the instance is not the latest when memory or disk capacity is expanded, it will be upgraded to the latest. In this case, enabling the QuickChange mode will cause the database to restart.
Will the instance restart if the QuickChange mode is enabled?
The instance needs to be restarted in some cases. A prompt will appear asking if you want to restart the instance on the configuration adjustment page.
Note:
If the instance is running the latest kernel minor version, it won’t restart if you only adjust the disk capacity in the QuickChange mode.
How do I know whether the QuickChange mode is enabled when I upgrade instance configuration in the console?
You can check the QuickChange switch on the configuration adjustment page: if the switch is toggled on, the QuickChange mode is enabled; otherwise, the mode is disabled.
How do I know whether the QuickChange mode is enabled when I use APIs to adjust instance configuration?
APIs do not support QuickChange for the time being, so instance configuration can be adjusted only by migrating data if you use APIs. APIs will support QuickChange in the future.
Will database parameters be modified during database configuration adjustment?
The innodb_buffer_pool_size parameter will be modified according to the configuration changes.
Will database parameters be modified during database configuration adjustment in the QuickChange mode?
It is the same with the normal mode. In the QuickChange mode, some parameters will be modified according to the configuration changes.
What is the difference between QuickChange mode and normal mode?
The QuickChange mode requires no data migration, so it takes less time to adjust instance configuration.
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