The lusdebug Command Fails

If the lusdebug command fails, review these suggestions to identify the potential problems and their solutions:

• Issue the sjiinq command as root, and provide the control-port as an argument. You should receive a message similar to the following:

scsidev@0.6.0:<EXABYTE EXB-10i EXB-10i >

Verify that the information supplied by the message is correct.

If the vendor and model names are incorrect, you supplied the wrong SCSI ID as the device ID during the driver installation. The installation script asks for the SCSI ID of the robot mechanism, not the tape drive.

• Deinstall the device driver and then reinstall it, and supply the correct address for the autochanger (robotic arm). Make sure that each device on the SCSI bus has a different SCSI ID address.

• Inspect the following items to verify that the autochanger is properly connected:

  • Make sure all the connectors on the SCSI bus are firmly connected.

  • Make sure none of the SCSI cables are defective.

  • Verify that the SCSI bus is properly terminated and is within the length specified by ANSI SCSI-II specifications (ANSI X3.131-1994).

    Both ends of the SCSI bus must be terminated with the appropriate resistors to be properly terminated. Single-ended SCSI buses are 220 ohms to +5 VDC, 330 ohms to ground. Differential terminators have a 122-ohm characteristic impedance (-5 VDC to +5 VDC). The ends of the SCSI bus are considered to be the last SCSI device at either end of the bus, where both peripheral devices and systems are considered as peer SCSI devices.

    Additional termination (termination placed on devices not at either end of the SCSI bus) is ill-advised. Additional termination causes the hardware bus drivers on each device on the bus to have to work harder (for example, out of the range of their nominal specification) to affect signal transitions. As a result, they may not be able to meet the timing requirements for some signal transitions.

    SCSI bus length limitations affect the quality of the signals; thus, the likelihood of transmission errors on the bus. For Single-ended SCSI buses (the most prevalent), the length is 6 meters, unless FAST SCSI devices are attached and in use, in which case the length limit is 3 meters. This length includes the length of the bus as it is within a device as well as the length of external cables. A reasonable rule of thumb for internal length is to assume 1 meter of internal bus length for the workstation chassis and about 0.25 meters per device for external peripheral boxes.

    Differential option SCSI buses can be much longer (due to the electrical differences from Single-Ended). Allow for a maximum of 25 meters. Never mix Differential and Single-Ended devices.

• Check to see whether an old autochanger driver is still installed. This can be the AAP driver shipped with earlier versions of Backup, or release 1.1 or earlier of the Parity driver, which only supported SCSI bus 0.

• Check the SCSI IDs on all devices attached to the same bus; make sure that none are the same. If two devices have the same target ID, you may experience the following symptoms: SCSI bus reset errors appear in system log files, the machine does not boot, and the probe-scsi boot prompt command on SPARC systems hangs.

• If the sensor that verifies whether the tape drive door is open is out of place, follow the instructions provided with your autochanger hardware to determine the problem, or contact your hardware vendor.

• If the autochanger is in sequential mode, change the setting to random mode.

If none of these suggestions resolve the problem, contact SunSoft Technical Support. You need to provide the information described in "Information to Gather Before You Call Technical Support ", and the captured output of the sjiinq, and sjirjc programs. See Appendix B, Command Line Reference Utilities for information on the jbexercise, sjiinq, and sjirjc programs, or refer to the associated man pages for each program.