Cabling the disk shelf SAS data ports

By cabling the serial-attached SCSI (SAS) ports, you can enable each controller in the HA pair to access its own disks and the disks of its partner controller.

About this task

Disk shelf cabling is always isolated within the HA pair that owns the disks. Disk shelves are never connected to other HA pairs in the cluster.

QSFP to QSFP SAS cables are used to connect disk shelves together and to connect disk shelves to the SAS ports on the controller.

Attention: It is possible to insert the QSFP connector incorrectly (upside down). The connector can slide in and even appear to click into place. However, the latch cannot engage unless the connector is inserted correctly. After inserting the cable, pull on the connector to ensure that it is latched.

For disk shelf I/O modules and controller onboard SAS ports, the cables must be inserted with the bottom of the connector facing down, as shown in the following image. The bottom of the connector is slightly longer than the top, and the latch release is typically on the bottom.

For controller SAS ports on add-in cards, the orientation depends on the slot in which the SAS card is installed. Insert the connector gently, and be sure that it latches securely. If the connector does not latch, rotate it 180 degrees and try again.

These instructions assume two stacks of disk shelves per HA pair. You can split your disk shelves into additional stacks to increase I/O throughput. Additional stacks require adding additional SAS ports to the storage controllers.

SAS ports on both controllers and disk shelves are indicated by the symbol.

1. Starting with the first stack of disk shelves, cable the I/O modules of the stacks to each other.
   1. Connect the IOM A SAS port with the circle symbol from the first shelf to the IOM A SAS port with the square symbol on the second shelf.
   2. Continue connecting IOM A ports on the remaining disk shelves in the stack, from the ports with a circle symbol to the ports with a square symbol.
   3. Connect the IOM B SAS port with the circle symbol from the first shelf to the IOM B SAS port with the square symbol on the second shelf.
   4. Continue connecting IOM B ports on the remaining disk shelves in the stack, from the ports with a circle symbol to the ports with a square symbol.
   Example

   The following example displays the DS2246 disk shelf cabling:

   
   
   

   The following example displays the DS424x disk shelf cabling:

   
   
   
2. Repeat Step 1 for each stack of disk shelves.
3. Connect the first set of controller-to-shelf SAS cables.
   1. Connect the controller 1 SAS port 0a to the SAS port with the square symbol on the first disk shelf in the first stack.
   2. Connect the controller 1 SAS port 0c to the SAS port with the square symbol on the first disk shelf in the second stack.
      This step is not applicable to the FAS8020.
   3. Connect the controller 2 SAS port 0a to the SAS port with the square symbol on the second disk shelf in the first stack.
   4. Connect the controller 2 SAS port 0c to the SAS port with the square symbol on the second disk shelf in the second stack.
      This step is not applicable to the FAS8020.
   Example

   The following example displays the first set of controller-to-shelf cabling with DS2246 disk shelves:

   
   
   

   The following example displays the first set of controller-to-shelf cabling with DS424x disk shelves:

   
   
   
4. Connect the last set of controller-to-shelf SAS cables.
   1. Connect the controller 1 SAS port 0b to the SAS port with the circle symbol on the last disk shelf in the last stack.
   2. Connect the controller 1 SAS port 0d to the SAS port with the circle symbol on the last disk shelf in the first stack.
      This step is not applicable to the FAS8020.
   3. Connect the controller 2 SAS port 0b to the SAS port with the circle symbol on the next-to-last disk shelf in the last stack.
   4. Connect the controller 2 SAS port 0d to the SAS port with the circle symbol on the next-to-last disk shelf in the first stack.
      This step is not applicable to the FAS8020.
   Example

   The following example displays the last set of controller-to-shelf cabling with DS2246 disk shelves:

   
   
   

   The following example displays the last set of controller-to-shelf cabling with DS424x disk shelves:

   
   
   
5. Repeat all steps for the other HA pairs in the cluster.