that should be simple, but I cannot figure that out
Amazon bills the real used storage amount for Aurora databases, not the allocated storage like for non-Aurora.
there is a metric VolumeBytesUsed - The amount of storage used by your Aurora DB instance. This metric applies to an entire Aurora DB cluster, not for instance. https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Monitoring.html
I have a cluster of 1 Arora Writer and 2 Readers. DB size is about 10 Gb and VolumeBytesUsed shows 10Gb. According to documentation, each Aurora node has its own data copy - https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Overview.html So if I have 10Gb DB - Aurora Writer and 2 Readers should be using 10x3 = 30 Gb of storage, but VolumeBytesUsed shows 10Gb
Will I be billed for 10 Gb or 30 Gb in that case?