Just say you have a device /dev/sdd that you want to pass through to a guest machine. When you configure it under vmware you can't use the normal nomenclature (ie /dev/sdd), you must pass through the "sg" device (ie /dev/sg3)
The trouble is, sometimes it is hard to figure out which sg device is which.
The answer is to use the "sg_map" command.
sudo apt-get install sg3-utils
brettg@jupiter:~# sudo sg_map