An RDS DB instance's allocated storage keeps approaching capacity as data grows, and the team wants AWS to increase the storage automatically without any downtime or manual intervention, up to a limit they define. Which RDS feature should they enable?
- Multi-AZ deployment
- A larger DB instance class
- RDS storage autoscaling, which increases allocated storage when free space drops to a low threshold
- Manual storage modification triggered by a CloudWatch alarm
Why C? And why not the others?
Correct answer: C. RDS storage autoscaling, which increases allocated storage when free space drops to a low threshold
RDS storage autoscaling monitors free storage space and, once it drops to roughly 10 percent or less of allocated storage for a sustained period, automatically increases the allocated storage in the background, online, up to a maximum threshold the administrator configures, requiring no downtime or manual action. The option describing Multi-AZ is wrong because Multi-AZ addresses availability and failover through a synchronized standby; it has no bearing on how much storage is allocated to the instance. The option describing a larger DB instance class is wrong because instance class governs compute resources such as vCPU and memory, not the storage volume attached to the database, and resizing the instance class does not add storage. The option describing a manually triggered CloudWatch alarm is wrong because that describes a custom, human-built automation the team would have to design and maintain themselves, which is precisely the manual intervention the built-in storage autoscaling feature is meant to eliminate.
Source: AWS RDS documentation: managing capacity automatically with Amazon RDS storage autoscaling