Background
For ApsaraDB RDS for MySQL and ApsaraDB RDS for PostgreSQL High-availability Edition instances that use cloud disks, automatic storage expansion previously applied only to the primary instance. When the primary instance expanded, read-only instances did not expand alongside it, which caused two problems:
ApsaraDB RDS for MySQL: A read-only instance with insufficient storage capacity could not sync data with the primary instance after the primary instance expanded.
ApsaraDB RDS for PostgreSQL: The primary instance's automatic storage expansion failed if any associated read-only instance had less storage capacity than the primary's target capacity.
For instructions on configuring automatic storage expansion, see Configure automatic storage expansion for an ApsaraDB RDS for MySQL instance and Configure automatic storage expansion for an ApsaraDB RDS for PostgreSQL instance.
What changed
When a primary High-availability Edition instance (cloud disk) triggers automatic storage expansion, the system now checks the storage capacity of each associated read-only instance before expanding the primary instance.
| Read-only instance storage capacity | Action |
|---|---|
| Greater than or equal to the primary instance's target capacity | The read-only instance is not expanded. |
| Less than the primary instance's target capacity | The read-only instance is expanded first. After all read-only instances meet the required capacity, the primary instance expands. |
Effective date
Starting February 28, 2023, this change rolls out in phases across Alibaba Cloud regions.
Effect
ApsaraDB RDS for MySQL: Eliminates data synchronization failures caused by insufficient storage capacity on read-only instances after a primary instance expansion.
ApsaraDB RDS for PostgreSQL: Eliminates primary instance automatic storage expansion failures caused by insufficient storage capacity on read-only instances.