Guideline for MySQL free space What is the guideline for how much free space to keep available on a MySQL AWS RDS instance (SSD)? In the past for an on-premises SQL Server install we used to use something like 2x the largest table in the database as this would provide enough space for maintenance tasks etc. and plenty of reaction time for unexpected growth. Are there any such guidelines for a MySQL RDS install? (We were recently caught running far too lean and a few poorly constructed queries led to an insufficient space message).
A really poorly constructed query can take a huge amount of space -- can't really protect from that.

Your maintenance?  Or AWS's maintenance?

If you can 'quickly' upgrade to a bigger instance, would that be an acceptable fix for nearly running out of space?

Would you like a review of the schema for the largest table?  Maybe some datatypes could be shrunk.  Maybe some normalization is feasible.  Maybe unhexing uuids, etc, is advisable.  Etc.

Otherwise, stick with your old rule of thumb.