A DS14mk2 or DS14mk4 have two of what is know as a electronically switched hub (ESH) module in them. They are labled A and B. Each esh has an in and an out port. If you connect 1 filer to the A port and the other filer to the B port, both filers can see the disks and you have an active / active cluster. So if a cable is pulled out or a HBA laser dies, the second filer can take over.
In a HA environment. The 1st filer is conected to the A port in but also the B port out. The is reversed on the 2nd node B in and A out. This is HA in an active / active enviroment.
If you just have a single file put one cable to the A and the other to the B.
You can see if it is working
storage show disk -p
Have a look at page 16 & 17
http://media.netapp.com/documents/tr-3437.pdf
Hope this help
Brendon