Which DB at AWS:

https://aws.amazon.com/products/databases/

Also shouldn't AWS warn them that this was about to happen?

Edit 1:

DynamoDB says: "There is no practical limit on a table's size. Tables are unconstrained in terms of the number of items or the number of bytes."

The SQL databases say this: "The Amazon Aurora engine will automatically grow the size of your database volume as your database storage needs grow, up to a maximum of 64 TB or a maximum you define. The MySQL, MariaDB, Oracle, and PostgreSQL engines allow you to provision up to 6 TB of storage on-the-fly with zero downtime."

So they either hit 64TB or 6TB of data I assume?

EDIT 2:

According to this they are MySQL based: https://medium.com/making-instapaper/rebuilding-instapaper-s...

They could be on aurora though since many people just consider it to be mysql. It's a pretty painless migration from mysql as long as you are 5.6 or below. You can just replicate over to it live.

Think you need to set up CloudWatch to get alerts.

And CloudWatch is free for RDS at 5-minute collection intervals which is more than adequate for alerting on things such as "Am I about to hit the space limit on my database?"