I'm currently in the process of creating a new database, and have previously only ever used a single data file and a single log file. I've done some research online regarding the benefits of multiple data files, but I've found mixed opinions regarding the benefits of multiple data files on a single disk. So my question is: if the only disk available to me is a SAN disk would I see any performance benefits (such as multithreading/parallel processing) from splitting the data into 4 separate files? Would I be better of with a single file?
Also would there be any performance benefit of separating the indexes (and possibly an archive table) into their own filegroups on separate files on the same disk? Would this only provide administrative benefits?