The fas270 is really a DS14mk2-FC disk shelf with a cpu module instead of a shelf controller module and can only operate at 1gb. Here is a snippet from the DS14mk2-FC Service Guide:
The 1-Gb loop speed
setting must be used if
the disk shelf is
connected to the
FAS270.
and from the fas270 installtion guide:
Verify that the appliance speed (and disk shelf
loop speed, if applicable) is set to 1 Gb.
Also, the shelf id's only go from 1 to 7. Here is another snippet from the DS14mk2-FC service guide.
Each disk shelf in a loop must have a unique ID. A valid shelf ID is from 1
through 7
and a snippet from the FAS270 installation guide:
Set your appliance ID to 1.