Storage shelf rear panel
The PCMs, located on the left and the right sides of the storage shelf, contain fans.
The I/O module canisters are located in the center of the rear panel, one on top of the other. Each I/O module contains three mini-SAS HD ports; A, B, and C. The mini-SAS HD ports connect the I/O modules to the appliance and to other storage shelves. Note that the port labels are reversed on the bottom canister. Port C is not used at this time.
The PCMs and the I/O modules include LEDs.