We have a RHEL5 box with a 2.6.18 kernel up and running (no RAID in use, but the SAS controller is enabled in the BIOS). To expand the storage, we bought a 2TB drive to add to the machine. Currently the setup is like this:
SATA-0 => DVD-rom
SATA-1 => DVD-rom
SATA-2 => empty
HD-0 => old hard disk
HD-1 => old hard disk
HD-2 => new 2TB drive
HD-3 => empty

The BIOS doesn't seem to have any way to list the drive on any of the HD ports, only the SATA ports, so I'm not sure if the drive is being recognized or not. fdisk -l doesn't seem to recognize the 2 TB drive.

I'm going to try reordering the drive ports and try the drive in another machine, but I'm baffled here...

Not sure what the problem is here. The Dell SAS 6 controller can't seem to find the drive if it's plugged into one of the four "HD" SATA ports. I finally just plugged it into the "extra" SATA-2 port, and it seems to be fine. I wonder if it could be recognized after formatting...