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Cabling the disk shelf SAS data ports

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

Before you begin

You must have located and marked which disk shelves go with each storage 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 diagram. The bottom of the connector is slightly longer than the top, and the latch release is typically on the bottom.

Image shows QSFP connector as described in the text.

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. See the Universal SAS and ACP Cabling Guide if you want to use additional stacks of disk shelves.

Steps

  1. Set the disk shelf ID numbers for each disk shelf.

    Note: The disk shelf ID numbers might have been set in the factory.

    The shelf IDs in the first stack should be set to 10, 11, 12, and so on, with the first shelf ID set to 10. The second stack IDs should be 20, 21, 22, and so on. The third stack IDs should start with 30, the fourth stack IDs with 40, the fifth stack IDs with 50, and the sixth stack IDs with 60. This pattern makes it easy to keep track of each stack. IDs must be unique within an HA pair.

    1. Temporarily connect power cords to the disk shelf, and then turn on the power to the disk shelf.
    2. Remove the left ear cover from the shelf.
    3. Press and hold the U-shaped tab above the LEDs (DS4243) or shelf ID button (DS2246) until the first digit blinks.
    4. Press the tab or button until the correct number is displayed.
    5. Repeat steps c and d for the second digit.
    6. Press and hold the tab or button until the second number stops blinking.

      Both numbers blink and the operator display panel fault LED illuminates in about five seconds.

    7. Power-cycle the disk shelf to make the new disk shelf ID take effect.
  2. Starting with the first stack of disk shelves, cable the I/O modules of the stacks to each other as follows.

    If your system has only one disk shelf per stack, skip this step.

    1. Connect the IOM A SAS port with the round symbol from the first shelf to the IOM A SAS port with the square symbol on the second shelf.

      IOM A is either on the top or on the left, depending on your disk shelf model.

    2. Continue connecting IOM A ports on the remaining disk shelves in the stack, from the ports with a round symbol to the ports with a square symbol.
    3. Connect the IOM B SAS port with the round symbol from the first shelf to the IOM B SAS port with the square symbol on the second shelf.

      IOM B is either on the bottom or on the right, depending on your disk shelf model.

    4. Continue connecting IOM B ports on the remaining disk shelves in the stack, from the ports with a round symbol to the ports with a square symbol.

    Example

    Image shows two stacks of three disk shelves each and the SAS cables connecting the disk shelves within each stack.

  3. Repeat all previous steps for each stack of disk shelves.

    If your system has only one disk shelf per stack, skip this step.

  4. Connect the first set of controller-to-shelf SAS cables as shown in the following diagram.

    These instructions use two quad SAS cards in slots 11 and 12. If your SAS cards are in different slots, adjust the port numbers for the slots actually used. For two stacks of disks, you do not use two ports on each card. However you still need two cards to avoid a single point of failure.

    Example

    Image shows SAS cables connecting the two storage controllers to the two stacks of disk shelves as described in the text.

    1. Connect controller 1 SAS port 11a to the SAS port with the square symbol in I/O module A of the first shelf in the first stack.
    2. Connect controller 2 SAS port 11a to the SAS port with the square symbol in I/O module B of the first shelf in the first stack.
  5. Connect the next set of SAS cables as shown in the following diagram:

    Example

    Image shows SAS cables connecting the two storage controllers to the two stacks of disk shelves as described in the text.

    1. Connect controller 1 SAS port 11c to the SAS port with the square symbol in I/O module A of the first shelf in the second stack.
    2. Connect controller 2 SAS port 11c to the SAS port with the square symbol in I/O module B of the first shelf in the second stack.
  6. Connect the next set of SAS cables as shown in the following diagram:

    Example

    Image shows SAS cables connecting the two storage controllers to the two stacks of disk shelves as described in the text.

    1. Connect controller 1 SAS port 12b to the SAS port with the round symbol in I/O module B of the last shelf in the first stack.
    2. Connect controller 2 SAS port 12b to the SAS port with the round symbol in I/O module A of the last shelf in the first stack.
  7. Connect the final set of SAS cables as shown in the following diagram:

    Example

    Image shows SAS cables connecting the two storage controllers to the two stacks of disk shelves as described in the text.

    1. Connect controller 1 SAS port 12d to the SAS port with the round symbol in I/O module B of the last shelf in the second stack.
    2. Connect controller 2 SAS port 12d to the SAS port with the round symbol in I/O module A of the last shelf in the second stack.
  8. Repeat all steps in this topic for the other HA pairs in the cluster.