Cannot set secondary hard drive offline in Disk Management

A hard drive is a physical device (disk). A partition and a volume are essentially the same thing: a logical structure on the physical disk for the file system. The system drive is where the OS boot files are located (Boot folder, bootmgr, etc.). The system drive doesn't show up in the hard drives because it's not a hard drive, it's a volume (partition).

Also, you'll notice in Disk Management that the hard drives are listed as Disk 0, Disk 1, etc. and the volume structure (layout) of each disk is listed to the right of each disk in the lower pane.

Thanks JMreicha and Chopper3. I've solved the issue, there was indeed a zoning issue, but even more importantly the fiber was apparently run wrong. I hadn't done a lot (ok, practically no) fiber channel zoning experience before and screwed up the way the fiber switches were connected. I've corrected the issue, fabricA is now connecting just fine over fiber switches 1 and 3 and fabricB is now connecting over fiber switches 2 and 4. All uplink ports on the switches are set to E ports, and all host ports are E and F. All zoning is complete and SQL clusters are being built as I type this out.