Have you tried the ultimate boot disk? Lots of drive diagnostic tools there. I'm not sure if RAID will change anything, though the smart readers should work ok.
Is this a server ? if it is look for the orenge lights on the front but really it's a raid 5 wait till the drive fails then open your software that you configured your raid in see what drive failed look for that sata or scsi port replace drive go back into software start rebuild 12 to 24 hours later good to go...