I believe the modus operandi for most personal cloud storage providers here is to make the entire dataset read- and delete-only until the user gets enough stora

I believe the modus operandi for most personal cloud storage providers here is to make the entire dataset read- and delete-only until the user gets enough storage space (by upgrading or deleting files) to be able to write/upload again. That, plus some incessant push messages to your client devices about upgrading, which is annoying but expected.