This topic describes the limits and usage notes of ApsaraDB RDS.

After you create an RDS instance, you do not need to perform basic database O&M operations, such as high availability configuration and security patching. However, you must take note of the items that are described in the following table.

Item Description
Specification change When you change the specifications of your RDS instance, ApsaraDB RDS may migrate the data of your RDS instance to a new RDS instance. The incremental data that is generated in your RDS instance during the migration process continues to be synchronized to the new RDS instance. After the migration process is complete, ApsaraDB RDS switches your workloads over to the new RDS instance during the switching time that you specify. During the migration process, network interruptions or transient connections may occur. The actual situation varies based on the RDS edition that is used. If network interruptions or transient connections occur, you cannot perform most of the operations that are related to databases, accounts, and network settings.
Note
  • If your RDS instance runs the RDS Basic Edition, your RDS instance is not provided with a secondary RDS instance as a hot standby. When you change the specifications of your RDS instance, your database service is unavailable for 30 minutes or more. We recommend that you change the specifications of your RDS instance during off-peak hours to prevent interruptions to your workloads.
  • If your RDS instance does not run the RDS Basic Edition, a transient connection that lasts about 30 seconds may occur when you change the specifications of the instance. The transient connection does not interrupt your workloads. However, we still recommend that you change the specifications of your RDS instance during off-peak hours. Otherwise, make sure that your application is configured to automatically reconnect to your RDS instance.
  • In most cases, if your RDS instance is equipped with standard SSDs or enhanced SSDs (ESSDs) and does not run the RDS Basic Edition, no transient connections occur when you increase the storage capacity of the instance.
Version upgrade When you upgrade the major engine version or update the minor engine version of your RDS instance, network interruptions or transient connections may occur. The actual situation varies based on the RDS edition that is used. If network interruptions or transient connections occur, you cannot perform most of the operations that are related to databases, accounts, and network settings.
Note
  • If your RDS instance runs the RDS Basic Edition, your RDS instance is not provided with a secondary RDS instance as a hot standby. When you upgrade the database engine version of your RDS instance, your database service is unavailable for 30 minutes or more. We recommend that you upgrade the database engine version of your RDS instance during off-peak hours to prevent interruptions to your workloads.
  • If your RDS instance does not run the RDS Basic Edition, a transient connection that lasts about 30 seconds may occur when you upgrade the database engine version of the instance. The transient connection does not interrupt your workloads. However, we still recommend that you upgrade the database engine version of your RDS instance during off-peak hours. Otherwise, make sure that your application is configured to automatically reconnect to your RDS instance.
Failover In the RDS High-availability Edition or the RDS Enterprise Edition, your RDS instance is provided with a secondary RDS instance as a hot standby. If your RDS instance unexpectedly exits, your database services can fail over to the secondary RDS instance within 30 seconds. During the failover process, a transient connection that lasts about 30 seconds occur. We recommend that you configure your application to automatically reconnect to your database system. This allows you to prevent interruptions to your workloads.
Network change When you migrate your RDS instance between the classic network and a virtual private cloud (VPC), the server on which your application runs is disconnected from your RDS instance. In addition, the IP addresses of your RDS instance change. After the migration process is complete, we recommend that you immediately update the endpoint configuration on your application.
Data restoration Before you restore the data of your RDS instance, we recommend that you back up the important data on your RDS instance to prevent data loss. We also recommend that you restore the data of your RDS instance by using a temporary RDS instance or a cloned RDS instance. You must first create a temporary RDS instance or a cloned RDS instance. Then, you can restore the data of your original RDS instance to the temporary RDS instance or the cloned RDS instance. After you verify the data on the temporary RDS instance or the cloned RDS instance, you can migrate the data back to your original RDS instance.
Storage capacity If the storage capacity of your RDS instance is exhausted, ApsaraDB RDS locks the instance. In this case, you can only read data from the instance. We recommend that you check the storage usage on a regular basis.
Performance optimization
  • You must check whether the number of cores, memory capacity, IOPS, storage capacity, and maximum number of connections for your RDS instance are sufficient. If the performance of your instance are insufficient to meet your business requirements, you can optimize your database or upgrade the specifications of your RDS instance.
  • You must check whether your RDS instance runs as expected. For example, you can check whether a large number of SQL statements are executed at low speeds, whether SQL statements need to be optimized, and whether specific indexes are unnecessary or missing. If an issue is identified, you must resolve the issue to optimize the performance of your RDS instance.

Limits on database engines