Dell Unity™ All Flash and Unity Hybrid Hardware Information Guide

Link control card functions and features

The LCC supports, controls, and monitors the DAE, and is the primary interconnect management element. Each LCC includes connectors for input and output to downstream devices.

The LCCs in a DAE connects to the storage processors and other DAEs. The cables connect the LCCs in a system in a daisy-chain topology.

Internally, each DAE LCC uses protocols to emulate a loop; it connects to the drives in its enclosure in a point-to-point fashion through a switch. The LCC independently receives and electrically terminates incoming signals. For traffic from the system's storage processors, the LCC switch passes the signal from the input port to the drive being accessed; the switch then forwards the drive output signal to the port.

Each LCC independently monitors the environmental status of the entire enclosure, using a microcomputer-controlled monitor program. The monitor communicates the status to the storage processor, which polls disk enclosure status. LCC firmware also controls the SAS Phys and the disk-module status LEDs.

An enclosure ID, sometimes referred to as the enclosure address (EA), indicator is located on each LCC. Each LCC also includes a bus (back-end port) identification indicator. The SP initializes the bus ID when the operating system is loaded.

3U, 15-drive DAE LCC connectors and LEDs

Each 3U, 15 (3.5-inch) DAE LCC shows the following ports, LEDs, and connectors:

Table 1. 12-Gb/s LCC ports, LEDs, and connectors

Location	Description	Location	Description
	LCC management port (RJ-12) (not used)		Captive screw
	12-Gb/s SAS ports		Part number label
	Enclosure ID display		LCC power LED
	LCC fault LED		SAS port status LED
	Back-end (BE) bus ID display

Review Table 2 for the LED descriptions and status meanings.

Table 2. 12-Gb/s LCC LEDs

LED	Location	Color	State	Description
LCC fault LED		Amber	On	Fault within the LCC
		—	Off	No fault or powered off
LCC power LED		Blue	On	Powered on and no fault
		—	Off	Powered off
SAS port status LED		Amber	On	SAS port faulted
		Blue	On	SAS port linked up
		—	Off	No connector in port