Are cascading replicas still a thing for RDS MySQL?

Question

I can find traces on the internet that this was an option a while back, at least for MySQL 5.7 (for example: https://aws.amazon.com/rds/faqs/ still says: Amazon Aurora, Amazon RDS for MySQL and MariaDB: You can create a second-tier read replica from an existing first-tier read replica.)

Despite all the effort I can't figure out how to add a second tier read replica to an "first tier" replica of a MySQL 5.8 master. The option "Create read replica" is simply disabled if I have selected a read replica. The option to "Create Aurora read replica" is however prominently available.

So... Can anyone tell, Is it just me or has this option been dropped to drive more people towards Aurora?

Answer 1

Well, I figured it out.

It's necessary to enable backups for the first tier replica. That is, set the "Backup retention period" higher than 0.

Makes sense in retrospect.