Instance breakdown may occur due to insufficient disk capacity. To prevent instance breakdown and ensure service availability, Message Queue for Apache Kafka dynamically controls the disk usage of each instance.
- If the disk usage of an instance is lower than 75%, expired messages on the instance are deleted at 04:00 every day.
- If the disk usage of an instance is higher than or equal to 75% and lower than 85%, expired messages on the instance are regularly deleted to lower the disk usage to a value less than 75%.
- If the disk usage of an instance is higher than or equal to 85% and lower than 95%, messages stored on the Message Queue for Apache Kafka broker are deleted from the earliest one, no matter whether their retention period expires.
- If the disk usage of an instance reaches 95%, no more messages can be sent to the instance. This ensures service availability.
- To ensure service reliability and message backtracking capabilities, we recommend that you maintain the disk usage of an instance lower than or equal to 70%.
- For more information about why expired messages are retained, see Why is an expired message retained?.