Tips for how to size an Oracle server

I have not seen any sites or other pieces of information that would give you the information that you seek. And I would be leery of the information presented. The amount of memory, processors, and other system resources are not dictated by the total volume of data in the database.

Rather, the system resources are dictated by usage patterns. I've had 10TB databases that used less CPU than 100GB database. It all depends on how that data is getting used. The best way to size the server is to analyze the usage patterns on an existing server. Does your buffer cache need more memory to support the application with this data? Are your CPUs getting maxed out? I typically use existing knowledge to guide future hardware procurements. In the absence of existing knowledge, I have always used estimates based on what I think is going to happen with the data. Other than sizing my storage, I rarely take the overall data volume into account.