Google Cloud SQL billing for mysterious extra storage

[egnor]

We have Google Cloud SQL instances as follows

As you can see, there's a total of:
5T + 10G = 5010G allocated for non HA (zonal) storage
250G + 250G + 1T + 1T + 200G = 2700G allocated for HA (regional) storage

(It's not very efficiently allocated but never mind that for now.) Meanwhile our billing report for Cloud SQL for the last 30 days looks like this

Looking at "Usage", the Zonal Storage (non-HA) line item shows 5010 gibi-month, which matches the provisioning. However, Regional Storage (HA) shows 3700 gibi-month, which is 1000G more than the 2700G of known provisioned instance storage.

Any idea why we could be getting charged for the extra 1000G of storage? What else could show up under "Cloud SQL for PostgreSQL Regional - Standard storage in Americas" besides direct instance storage? (I believe backup snapshots are accounted for elsewhere, but maybe ??replication?? of ??some kind??)

Is there some other dashboard I could look at to understand this?

[christianpaula]

Hi @egnor,

Welcome to Google Cloud Community!

I would highly suggest contacting Google Cloud Support to further check your Cloud SQL for PostgreSQL Regional and they can provide more detailed for that.

Thank you

[egnor]

The answer, for anyone else looking:

In general the best self-service way to resolve Cloud Billing discrepancies is to export Cloud Billing data to BigQuery -- the resulting dataset is FAR more detailed than anything the Billing interface shows, and lets you dive down to the individual instance, get hourly-granularity billing data, and see all three ends of the usage * price = cost computation.

In my particular case, it turned out that Google Cloud was somewhat zealously rounding 1500GB storage to "1T" for display (both at the top level and in the detail view), which confused me. (I think "1.5T" would have been a lot more appropriate... one significant digit, really??)