ApsaraDB RDS provides the following editions: Basic Edition, High-availability Edition, Cluster Edition, and Enterprise Edition. This topic describes RDS High-availability Edition.

RDS High-availability Edition is a widely used edition. RDS instances of this edition are deployed in a primary/secondary architecture to deliver highly available services. This edition is suitable for more than 80% of use cases in various industries, such as Internet, IoT, online retail, logistics, and gaming.

Note
  • The secondary instance serves as a standby for the primary instance and is inaccessible to outside services.
  • In extreme circumstances, RDS High-availability Edition may fail to prevent data loss. If you require 100% data security and zero recovery point objective (RPO), we recommend that you use RDS Enterprise Edition. For more information, see RDS Enterprise Edition.

Topology

Benefits

  • High availability

    In RDS High-availability Edition, the mode that is used to synchronize the data of the primary instance to the secondary instance varies based on the parameter template that you select. The semi-synchronous mode or asynchronous mode is used to synchronize data. If the primary instance becomes inaccessible, your database system fails over to the secondary instance.

    The primary instance and the secondary instance can reside in the same zone or in different zones of the same region.

    Note If the secondary instance becomes inaccessible, data of the primary instance is backed up in real time. When a backup is near completion, the FLUSH TABLE WITH READ LOCK (FTWRL) statement is executed. This triggers a global lock that is held for up to 5 seconds. When the global lock is held, the primary instance is in read-only mode.

  • Comprehensive functionality

    RDS High-availability Edition provides a complete suite of features, such as auto scaling, backup and restoration, performance optimization, read/write splitting, and SQL Explorer. The SQL Explorer feature stores the logs of all executed statements for up to five years. You can use the logs to trace operations performed on your databases, which helps ensure the security of your data.

Limits

For performance purposes, the primary and secondary instances must be deployed in the same region.

Upgrade the edition of an RDS instance to RDS High-availability Edition

RDS Basic Edition instances are deployed in a standalone architecture. Due to the lack of a hot standby, your business may experience extended periods of downtime when the RDS instance fails. This also happens when you change the specifications or upgrade the database engine. Therefore, if you require high service availability, we recommend that you use RDS High-availability Edition.

You can directly purchase RDS High-availability Edition or upgrade the edition of an RDS Basic Edition instance to RDS High-availability Edition. The upgrade is convenient as you do not need to migrate data to a new RDS instance or reclaim the original RDS instance.
Note

Create an RDS instance

FAQ

  • Can I establish a direct connection to my secondary RDS instance?

    No, direct connections cannot be established to secondary RDS instances. Direct connections can only be established to the primary RDS instance. A secondary RDS instance serves as a standby and cannot be accessed externally.

  • Can I downgrade an RDS instance from RDS High-availability Edition to RDS Basic Edition?

    No, you cannot downgrade from RDS High-availability Edition to RDS Basic Edition. If you want to downgrade from RDS High-availability Edition to RDS Basic Edition, you can purchase an RDS instance that runs RDS Basic Edition and migrate the data of your original RDS High-availability Edition instance to the new RDS instance. Then, release your original RDS instance. For more information, see Migrate data between RDS instances.

  • I am using RDS High-availability Edition. How do I change the data replication mode of the instance?

    For more information, see Change the data replication mode of an ApsaraDB RDS for MySQL instance.

  • I am using RDS High-availability Edition. Does the data replication mode change to the asynchronous mode if the secondary RDS instance handles heavier workloads than the primary RDS instance?

    Yes, if the secondary RDS instance handles heavier workloads than the primary RDS instance, the data replication mode is changed to the asynchronous mode. For more information, see Data replication modes.