Is it possible for a File server to run a database server ? how would that be classified at that point ?
No, conceptually that would not mean anything. A file server and a database server are discrete concepts.
A single operating system can run neither, either, or both. But as servers themselves, they are discrete.
I gotcha. It was one of those hypothetical questions
What's messy is that technical file servers are a very, very specific form of database server. Because a file server presents a file system over a network. And a file system is a special case database.
No one really thinks about this and absolutely no one will talk about file servers this way, but for understanding what is actually happening... file servers are special purpose database servers. And that is very easy to prove.
So a file server is a database server, but a database server is not a file server. But file servers are so common, unique, and discrete, we treat them as totally different animals and no one considers the two to even be similar.