Downtime when adding more storage to DB Instance

[wara]

The question in the practice exam is this

A production MySQL database hosted on Amazon RDS is running out of disk storage. The management has consulted its solutions architect to increase the disk space without downtime.

How can the solutions architect satisfy the requirement with the LEAST operational overhead?

The correct answer is Modify the DB Instance settings and enable storage autoscaling. That’s is alright.

Then there’s an incorrect option “Increase the allocated storage for the DB instance”. It’s only incorrect because it will incur a downtime. However, in the AWS document “Modifying an Amazon RDS Instance”, https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Overview.DBInstance.Modifying.html, it says that downtime doesn’t occur during that change. Maybe it should be incorrect because there’s an operational overhead not because it will incur a downtime. Can you clarify it pls, thanks

• This discussion was modified 2 years, 9 months ago by  wara.

[Carlo-TutorialsDojo]

Hello wara,

Thanks for your feedback.

Yes, you’re right. Technically, your application will still be able to connect to your database during the change. But it comes at the expense of a decrease in read/write IOPS. Your DBs ability to serve requests depends on different factors like how large its capacity (instance size) is and its configuration settings.

There was this one time when I tried to increase the storage of an RDS database. I noticed a huge spike in CPU utilization during the change rendering my application unusable for a few minutes. I think this is what I was going for when I created this question. But, yeah, technically the database remains available during the change. We will make some wording adjustments to the scenario so that it’ll fit the narrative described in the documentation.

Let me know if this answers your question.

Thanks and Regards,

Carlo @ Tutorials Dojo

[wara]

Hi Carlo,

Thanks for the acknowledgement and response. I hope this is helpful to everyone.

[Niko Borodachuk]

super helpful!