Question

A SysOps administrator configured a CloudWatch alarm on an RDS instance to publish to an SNS topic when FreeStorageSpace drops below a threshold. During recent testing, the metric clearly breached the threshold and the alarm state changed to ALARM in the console, but no SNS notification was ever delivered. The SNS topic works correctly when tested with a manual publish, and the subscription is confirmed. What is the MOST likely cause?

Accepted Answer

Alarm actions are disabled on the CloudWatch alarm, so no action fires when the state changes.

Answer

The alarm's evaluation period is too short, causing CloudWatch to suppress the notification.

Answer

RDS metrics cannot trigger SNS notifications because they are managed by the RDS service.

Answer

The SNS topic must be in the same Availability Zone as the RDS instance to receive alarm actions.