mitch.fh (1/2/2013)
I think that like the cost of parallelism at one point exceed the benefit there is a "break-even point" for database files.
Don't make the mistake of thinking that multiple files are necessary for multiple threads to access. It's an old myth. Any thread in SQL can issue IOs to any file at any time.
There is no advantage to having multiple files on the same LUN (well, performance advantage, there are other reasons one might spilt, for backup/restore options). There's also no performance degradation for large files. If you're taking about files on the same LUN, 1 file of 10 TB is the same as 10 files of 1 TB.
As for multiple contrary opinions, welcome to the internet :-D. Guess you'll have to research and see who's opinion you would trust.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability