I would second Tim's comments below about postgres, but I'm not sure about the file/database split as my site is not so large. I have at the moment about 80 courses, many not very big and our db is about 80MB, which is small. I'd imagine a busy site might have a DB of 2-3GB, but others with more experience will have to confirm that.
Ideally a separate server as you will get a faster site out of it (faster as in won't slow down under load rather than faster as in lower response times for one person using it) by sharing the load, but this is more expensive and more hassle. However, I think if you manage to fill 1 TB, then Moodle will have become so indispensable to your organisation that you will be able to hold them to ransom with the threat of it collapsing and get cash for any number of servers and support staff you like 
I would second Tim's comments below about postgres, but I'm not sure about the file/database split as my site is not so large. I have at the moment about 80 courses, many not very big and our db is about 80MB, which is small. I'd imagine a busy site might have a DB of 2-3GB, but others with more experience will have to confirm that.
I would second Tim's comments below about postgres, but I'm not sure about the file/database split as my site is not so large. I have at the moment about 80 courses, many not very big and our db is about 80MB, which is small. I'd imagine a busy site might have a DB of 2-3GB, but others with more experience will have to confirm that.