Also, if you're thinking of doing this; a dangerous and experimental idea that will probably end up losing data and corrupting your database (Google Cloud Storage is non-locking and probably non-consistent), I'll write a full-fledged guide at some point but these are a few pitfalls I ran into trying to set it up:
1. Make sure your instance has write access to your cloud storage bucket - calibre won't load and you will get an error relating to a capitalization test if you can't write to the bucket.
2. if you copy your calibre library to GCS using gsutil (or anything that's not gcsfuse), make sure to enable
with gcsfuse or else you won't get cover art or metadata showing up. Not sure if you can run this only once or youhave to mount it like this every time.