Andy is correct. The sdc is a kernel driver so needs the OS to already be installed and running on local disk. It isn't like FC where you see the lun at the HBA level before the system even boots into the os. 
Crazy question time.... Typically all our servers boot-from-san for their OS disks. Was wondering if anyone had attempted this with a ScaleIO volume. How did you go about it? 
Boot From ScaleIO Volume?