If you have a supported SCSI RAID controller, and have set up some sort of array (probably a RAID 5) with all three drives, e-smith will treat them as a single drive, and you'll need to use whatever maintenance utility came with the RAID controller to determine what drives are in use. If you don't have such a controller, e-smith will allow you to create a software RAID 1 (mirrored) array with two of the drives, but the third would not be used.