Dexter Filmore wrote:

Assuming one has 6 disks on two controllers and one dies, how does one tell 
the dead one? Which controller/port?

There are probably more elegant ways, but I use smartctl -a on the 
failed drive to find it's serial number and use this to find the 
location based on where I installed the drives initially, which I note 
in a text file or a label attached to the exterior of the case on 
machines with removable drive trays.

Regards,

Richard