Hardware RAID passthrough devices
This option can be used to add physical disks behind hardware RAID controllers when they are not detected automatically, but can be queried by smartctl through a passthrough device. Leave it empty unless you need to monitor disks behind such a controller.

For example, /dev/sg0 cciss 0 3 adds three cciss physical disks numbered 0, 1 and 2 through the /dev/sg0 passthrough device. The final value is the number of disks to add, not the last disk number.