It's not working with physical disks - it is working with your logical drives such as C:, D:, etc.  So what is doing the physical storage (eg, single IDE disk, SCSI disk, RAID 0, 1, 5, 10 etc) doesn't really matter.  I imagine you could even have it check it on a USB drive!

So if you have drives C & D on your RAID 10, as far as your apps (including SQL Server) are concerned, it doesn't matter that C & D are sharing the one set of disks.  SQL will care if it has a database on D and D has only 10MB left though!

Hope that helps explain...