Anyways this would imply that on X10 the mysql_connect statement makes a connection to the same machine the php server lives on.
Still wondering about differences between application server and file server in the MySQL context, but there's no hurry for that.
I think your question about servers will confuse most people on this site, rather than help them. This is because people typically refer to servers as the actual machine hosting the interaction w/ the client; to simplify: the hardware.
What you are questioning is in regards to virtual and/or application servers. These can reside on one or multiple machines, because it is software driven.
If you want to know more about the partitioning and tablespace management of MySQL or PostgreSQL, you will need to ask an admin by opening the ticket. My guess is that you still will not get a response, unless you're a paid member. In which case, if it truely affects your operations, then you would not be paying for hosting, you'd run your own dedicated server.
My guess, though, is that the services x10 provides is all on the same hard drive. This seems to be because when one goes offline (like Lotus), it doesn't effect any of the others.