Resolving communication errors

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Refer to a list of actions to identify and resolve communication errors with Fibre Channel devices.

Resolving errors with Fibre Channel communications

The following steps help you to identify the source of the problem and resolve the error. Perform these steps if the host is unable to communicate with one of more Fibre Channel devices in the library.
  1. Ensure that all Fibre Channel cables from the host to the library are securely connected at both ends. Also, check that the fibers are not crossed, and that there is light present out the end of the fiber.
  2. If multiple Fibre Channel drives exist on a single loop (as when multiple drives are connected to a hub), ensure that each device on the loop has a unique loop ID.
  3. Ensure that all Fibre Channel host adapters are supported (for a list of supported adapters, refer to http://www.ibm.com/servers/storage/tape/drives. Under the appropriate tape drive, select Product details. Then, select Host bus adapter. Or, contact your IBM® sales representative).
  4. Ensure that the appropriate levels of device driver are installed and that any other prerequisites are satisfied.
  5. Some Fibre Channel devices provide diagnostic routines that show all of the devices that are attached to them. Refer to the device documentation for details about the routines. If a Fibre Channel device that is positioned between the host and the library can see the library's devices, the problem is probably between the Fibre Channel device and the host.
  6. Ensure that the host is configured with the correct World Wide Node Name or World Wide Port Name.
  7. Refer to the problem determination information in the documentation for the device driver that you are using. If you are using the IBM device driver, refer to the IBM Tape Device Drivers Installation and User's Guide. Ensure that the device driver is loaded and that it can communicate with the tape drives:
    1. If the device driver is not loaded, install it.
    2. If the device driver is loaded but cannot communicate with the tape drives, call your IBM service representative.
    3. If the device driver is loaded and can communicate with the tape drives, but the application software cannot communicate with the tape drives, contact the provider of your application software for assistance.
  8. Current Fibre Channel components support various Fibre Channel speeds. Possible speeds are 1 Gb/s, 2 Gb/s, 4 Gb/s, 8 Gb/s. Refer to the machine configuration and ensure that all drives, switches, and host bus adapters use compatible speed settings.
  9. For an LTO tape drive, open the rear door of the library, locate the affected drive, and observe the status LEDs on the back of the drive canister. The LEDs have the following meaning:
    • Blank: no light is detected at the drive's Fibre Channel port. No light indicates one of the following conditions:
      • A Fibre Channel cable is unplugged at the drive or at the nearest Fibre Channel device (host bus adapter, switch, or hub).
      • A Fibre Channel cable is broken between the drive and the nearest Fibre Channel device (host bus adapter, switch, or hub).
      • The drive or the nearest Fibre Channel device (host bus adapter, switch, or hub) is powered off or has a hardware problem.
    • Yellow: Fibre Channel connections between the drive and the Fibre Channel device to which it is connected (host bus adapter, switch, or hub) are good, but communication is not established.
    • Green: Fibre Channel connections are good and communication is established.

Resolving errors with SAS communications

Check the host connections for your drive by following these steps. If your server is not communicating with the SAS drive, the problem might be with the SAS cable, the SAS host adapter, or the SAS host adapter setup.

  1. Check whether the tape drive power is ON.
  2. Verify that the SAS cable is connected properly to the server and to the tape drive.
  3. Check whether the parameters for the SAS host adapter installation are correct.
  4. Verify that the SAS host adapter is supported by the tape drive.
  5. Ensure that there is a point-to-point connectivity between the server and the tape drive. SAS connectivity does not support multiple drive connections (daisy-chaining of devices).