Why KillDisk doesn't display disk serials from drives hooked up to RAID controllers?

The software uses platform dependent device I\O functions to get serial numbers from hard drives.

Most, if not all, RAID controllers do not properly process these requests.

Typically, a RAID controller is used to hook up 2 or more hard drives in such a way that the operating system thinks it is one drive. Therefore, the operating system can not access the drives individually. When queried for a hard drive's serial number, the RAID controller does not know which serial number to return, so it does not return a serial number at all. All RAID controllers tested will do this even if there is only one drive in the RAID set.