ApsaraDB RDS:Use the automatic performance scaling feature

Automatic performance scaling process

Automatic scale-up

Automatic scale-down

• RDS instances that run RDS High-availability Edition and use cloud disks

  After you select Automatic Scale-down/in, an automatic scale-down is triggered after a cooldown period ends if the CPU utilization of your RDS instance is lower than 30% for longer than 99% of a scale-down observation window. The specifications of the RDS instance are scaled down to the original specifications in small increments.

  Important

  • A scale-down observation window equals the value of the Observation Window parameter plus 10 minutes. For example, if you set the duration of an observation window to 30 minutes, the duration of a scale-down observation window is 40 minutes.

  • If your RDS instance runs RDS High-availability Edition with cloud disks, the automatic scale-down feature can stably run on a new architecture. If the value of the kindCode parameter for the RDS instance is 18, the RDS instance uses a new architecture. You can call an operation to query the architecture of an RDS instance. For more information, see DescribeDBInstanceAttribute.

• RDS instances that run RDS Enterprise Edition and use general-purpose instance types

  If the CPU utilization of your RDS instance is lower than 30% for longer than 99% of a specified scale-down observation window, DAS scales the IOPS and the number of CPU cores of the RDS instance down to the original specifications.

Billing methods

• RDS instances that run RDS Enterprise Edition and use general-purpose instance types: You are charged based on the pay-as-you-go billing method. Fees are deducted once every hour.

  Fee calculation formula: (Fee per CPU core × Number of CPU cores added) × Scale-up duration in minutes

• RDS instances that run RDS High-availability Edition and use cloud disks: You are charged based on the instance type after scale-up. The scale-up pricing varies based on the instance configurations, such as the region and the new specifications. For more information, visit the ApsaraDB RDS buy page.

Example

After you enable the automatic performance scaling feature for a database instance, DAS automatically scales up the database instance during peak hours. This doubles the read/write throughput and lowers the CPU utilization from higher than 90% to 25%. The database instance can run under a heavy load for approximately 10 hours. After the traffic decreases and the CPU utilization drops to lower than 25%, DAS scales the database instance back to the original specifications.

This way, DAS manages your database instance to handle traffic spikes during peak hours and helps ensure the stability of your business.

Impacts

• If your RDS instance runs RDS High-availability Edition and uses cloud disks, an instance switchover may occur during a specification change. Make sure that your application is configured to automatically reconnect to the RDS instance. For more information about the impacts of an instance switchover, see Impacts of an instance switchover.

• If your RDS instance does not run the latest minor engine version, the system updates the minor engine version of the RDS instance to the latest version during a specification change. This ensures the performance and stability of your database service.

• The scaling operation is performed only on the primary RDS instance. If a primary/secondary switchover is triggered after the primary RDS instance is scaled up, one of the following situations occurs:

  • If the primary RDS instance (original secondary RDS instance) meets the conditions to trigger a scale-up or a scale-down, DAS performs the scaling operation on the primary RDS instance.

  • If the secondary RDS instance (original primary RDS instance) meets the conditions to trigger a scale-down, DAS scales the secondary RDS instance down to the original specifications.

Procedure

1. Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. Use one of the following methods to go to the Autonomous Function Management panel:

   • In the left-side navigation pane, choose Autonomy Services > Diagnostics. On the page that appears, click the Autonomy Center tab. On the Autonomy Center tab, click Autonomy Service Settings.

   • In the left-side navigation pane, choose Autonomy Services > Dashboard. On the Dashboard tab of the page that appears, click Autonomy Service Settings.

3. On the Autonomous Function Settings tab of the Autonomous Function Management panel, enable the autonomy service.

4. On the Optimization and Throttling tab, configure the following parameters:

   If your RDS instance runs RDS High-availability Edition and uses cloud disks, select Automatic Performance Scaling. If your RDS instance runs RDS Enterprise Edition and uses a general-purpose instance type, select Automatic Resource Elasticity.

   Instance category	Parameter	Description
   RDS instances that use general-purpose instance types	Average CPU Utilization ≥	The threshold based on which an automatic scale-up is triggered. If the average CPU utilization is greater than or equal to the specified threshold, automatic scale-up is triggered.
   RDS instances that run RDS High-availability Edition and use cloud disks	Observation Period	The period of time during which you want to observe the performance of the RDS instance. DAS checks the average CPU utilization of the RDS instance within the observation window at specific intervals. If the average CPU utilization reaches the specified threshold, automatic scale-up is triggered. Important A scale-down observation window equals the value of the Observation Window parameter plus 10 minutes. For example, if you set the duration of an observation window to 30 minutes, the duration of a scale-down observation window is 40 minutes.
   	Maximum Specifications	The maximum specifications to which DAS can scale up the RDS instance. If the CPU utilization of the RDS instance reaches the specified threshold, DAS scales up the RDS instance. If the CPU utilization of the RDS instance reaches the specified threshold again during the next observation window, DAS scales up the RDS instance again. This process is repeated until the RDS instance is scaled up to the maximum specifications that you specified.
   	Automatic Scale-down/in	After you select Automatic Scale-down/in, automatic scale-down is triggered after a cooldown period ends if the CPU utilization of your RDS instance is lower than 30% for longer than 99% of a scale-down observation window. The specifications of the RDS instance are scaled down to the original specifications in small increments. A scale-down observation window equals the value of the Observation Window parameter plus 10 minutes.
   	Quiescent Period	The minimum interval between two automatic scale-up or scale-down operations, which is referred to as a cooldown period. During a cooldown period, DAS monitors the CPU utilization of the RDS instance, but does not trigger automatic scale-up or scale-down even if the specified conditions are met. If a cooldown period and an observation window end at the same time and the average CPU utilization within the observation window reaches the specified threshold, DAS automatically triggers a scale-up or scale-down.
   RDS instances that run RDS Enterprise Edition and use general-purpose instance types	Scale-up Observation Window	The period of time during which you want to observe the performance of the RDS instance after a scale-up. DAS checks the average CPU utilization of the RDS instance within the observation window at specific intervals. If the average CPU utilization reaches the specified threshold, automatic scale-up is triggered.
   	Scale-back Observation Window	The period of time during which you want to observe the performance of the RDS instance after a scale-down. DAS checks the CPU utilization of the RDS instance within the observation window at specific intervals. If the CPU utilization is lower than 30% for more than 99% of the observation window, automatic scale-down is triggered.

5. Click OK.

FAQ

I want to scale up my RDS instance, but the specifications of the RDS instance have reached the upper limit. What do I do?

We recommend that you purchase an RDS instance that runs a higher RDS edition. For example, you can purchase an RDS instance that runs RDS High-availability Edition and uses a dedicated instance type. The dedicated instance family supports up to 104 CPU cores and 768 GB of memory. Then, migrate your RDS instance to the new RDS instance. For more information about the instance types and migration solutions, see Specifications of ApsaraDB RDS for MySQL instances and Migrate data between ApsaraDB RDS for MySQL instances.

References

• If traffic peaks occur within a fixed time period, you can use the scheduled auto scaling feature to configure policies and scale up the specifications of your RDS instance on a regular basis. After the specified scaling period elapses, your RDS instance is automatically restored to its previous specifications. For more information, see Use the scheduled auto scaling feature.

• If the instance type of your RDS instance does not support the automatic performance scaling feature, you can use the following methods:

  • You can change the specifications of an RDS instance, including scaling up and down specifications. For more information, see Change instance specifications.

  • You can change the instance type to meet the requirements for automatic performance scaling. For more information, see Change instance specifications.