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.

ItemDescription
Specification changeWhen 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 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 degree of impact varies across different RDS editions. If network interruptions or transient connections occur, you are unable to perform most of the operations that are related to databases, accounts, and network settings.
Important
  • RDS Basic Edition provides only a standalone instance. When you change the specifications of your RDS instance, your database service is unavailable for 30 minutes or longer. We recommend that you change the specifications of the RDS instance during off-peak hours to minimize the impact on your business.
  • Other editions aside from RDS Basic Edition may experience a transient connection that lasts approximately 30 seconds when you change the specifications of the RDS instance. This only slightly impacts your workloads. However, we still recommend that you change the specifications of your RDS instance during off-peak hours or 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 RDS Basic Edition, no transient connections occur when you increase the storage capacity of the RDS instance.
Version upgradeWhen you upgrade the major engine version or update the minor engine version of your RDS instance, network interruptions or transient connections may occur. The degree of impact varies across different RDS editions. If network interruptions or transient connections occur, you are unable to perform most of the operations that are related to databases, accounts, and network settings.
Important
  • RDS Basic Edition provides only a standalone instance. When you change the specifications of your RDS instance, your database service is unavailable for 30 minutes or longer. We recommend that you upgrade the major engine version or update the minor engine version of your RDS instance during off-peak hours to minimize the impact on you business.
  • Other editions aside from RDS Basic Edition may experience a transient connection that lasts approximately 30 seconds when you change the specifications of the instance. This only slightly impacts your workloads. However, we still recommend that you change the specifications of your RDS instance during off-peak hours or make sure that your application is configured to automatically reconnect to your RDS instance.
FailoverRDS High-availability Edition and RDS Enterprise Edition provide a secondary RDS instance that serves as a hot standby. If your primary RDS instance unexpectedly fails, your database system can fail over to the secondary RDS instance within 30 seconds.The period of time that is required for the failover may be longer if data inconsistencies exist between the primary RDS instance or primary node and the secondary RDS instance or secondary node. During the failover process, a transient connection that lasts approximately 30 seconds occurs. We recommend that you configure your application to automatically reconnect to your database system. This prevents interruptions to your workloads.
Network type changeWhen 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, and a new IP address is assigned to your RDS instance. After the migration process is complete, we recommend that you immediately update the endpoint configuration on your application.
Data restorationBefore 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 copying your data to a temporary RDS instance or a cloned RDS instance. After you verify the accuracy of the restored data, you can migrate the data back to your original RDS instance.
Storage capacityIf the storage capacity of your RDS instance is exhausted, the RDS instance is automatically locked and cannot provide services. We recommend that you check the storage usage on a regular basis.
Note If the storage usage is abnormally high, troubleshoot the issue based on the description in What do I do if my ApsaraDB RDS for MySQL instance is locked because its storage capacity is exhausted?
Performance optimization
  • You must check whether the number of cores, memory capacity, input/output operations per second (IOPS), storage capacity, and maximum number of connections for your RDS instance are appropriate for your use case. If the specifications do not meet your requirements, you can optimize or upgrade your RDS instance.
  • We recommend that you routinely check whether your RDS instance runs as expected, so that you can troubleshoot identified issues to ensure optimal performance. For example, you can check whether slow queries exist, whether SQL statements need to be optimized, or whether specific indexes are unnecessary or missing.

Limits on database engines