[Why isn't XYZ Provider available?]

would like to see support for rackspace

https://developer.rackspace.com/docs/cloud-files/v1/developer-guide/

[Paying for empty space on the cloud]

I'm unable to find another inquiry to this, hope I'm not be duplicative.  If I create a 5TB cloud drive on AWS or Google Cloud, does Clouddrive automatically create a 5TB chunk on the provider? or does it only store data that I've placed on the drive.  ie: if I create a 5TB drive and place 100GB of data on it, will I be incurring charges for 100GB of storage? or 5TB of storage?