Cabling Channel A

Channel A loop cabling exceptions

Generally, the Channel A loop in a cluster is cabled by connecting the FC-AL adapter in the node to the LRC, ESH, or ESH2 Input port of the first disk shelf in the loop, followed by cabling the disk shelves together. This process differs only by the type of Fibre Channel adapter you have in your cluster and the type of disk shelves you have.

Note
If you are cabling a cluster in a system cabinet, skip Channel A cabling and go to Cabling the cluster adapters. The Channel A loop is already cabled for you.

The following table lists exceptions to the general cabling process for the Channel A loop.

If you have...	Then...
Nodes using dual Fibre Channel adapters with any disk shelf type	You use optical cables to connect the nodes to the first disk shelf in the Channel A loop. The first port (labeled Port 1 on the adapter) of the dual Fibre Channel adapter is reserved for the Channel A loop.
DS14 or DS14mk2 FC disk shelves with nodes using copper FC-AL adapters	You use the HSSDC to DB-9 cable to connect the nodes to the first disk shelf in the Channel A loop.
DS14 or DS14mk2 FC disk shelves with ESH modules	All disk shelves must have ESH modules installed in them and you must not have mixed shelf-type loops. Use the supplied cables for your FC-AL adapters.
FC9 disk shelves with nodes using dual Fibre Channel adapters	Your first disk shelf LRC requires an MIA (media interface adapter) plugged into the Input port.

Cabling the Channel A loops

To cable the Channel A loops, complete the following steps, using the diagram for reference.

Note
All diagrams in this book show DS14 disk shelves. If you have other types of disk shelves, the Input and Output ports might be in different locations.

Step	Action
1	Cable the FC-AL adapter in Slot 8, Top port of the local node, to the disk shelf 1 Channel A LRC, ESH, or ESH2 Input port.
2	Cable the disk shelf 1 Channel A LRC, ESH, or ESH2 Output port to the disk shelf 2 Channel A LRC, ESH, or ESH2 Input port. Apply solid-colored labels to the cables.
3	Repeat Step 2, connecting output to input, for the remaining disk shelves in the loop.
4	Set the terminate switches to Off on all but the last disk shelf in the loop, then set the terminate switch on the last disk shelf to On. Note ESH2 modules are auto-sensing, and therefore do not have a terminate switch.
5	If you have...	Then...
	A mix of DS14 and DS14mk2 FC disk shelves with LRC modules	Set the 1/2 Gb switch to 1 Gb.
	A mix of DS14 and DS14mk2 FC disk shelves with ESH modules	Set the 1/2 Gb switch to 1 Gb.
	Only DS14mk2 FC disk shelves with ESH modules	Set the 1/2 Gb switch to 2 Gb.
6	Repeat Step 1 through Step 5 for the partner node.
7	Go to Cabling Channel B.