Service manual

Chapter 5 Troubleshooting
60
SCSI Subsystem Problems
An external SCSI subsystem does not work at installation
If your external SCSI subsystem does not work at installation, do the following:
1. Review the Troubleshooting Checklist before you continue.
2. Refer to the documentation provided with your SCSI devices for any specific installation
information.
3. If you added a SCSI controller board, ensure the board is properly installed and configured,
including no I/O address or interrupt conflicts.
4. Verify the external SCSI subsystem BIOS is being executed properly.
When the NetServer starts, the incrementing count of the RAM appears on the screen. Pressing
the Pause button stops the scrolling followed by pressing any key to continue. Then the external
SCSI BIOS displays a banner and a copyright notice.
Then the BIOS checks for valid devices on the SCSI bus, and reports which devices are found.
If you have installed and configured your SCSI devices correctly, you will see a list confirming
all SCSI devices installed in the system.
If the banner is not displayed, the external SCSI BIOS is not being executed.
5. Ensure an active terminator is installed at the end of the SCSI bus cable (chain), but there are
no other terminators used on the other devices.
NOTE When using LVD SCSI (often referred to as Ultra2 SCSI), termination is typically
provided at the controller and the far end of the cable.
6. Ensure there is no device set to SCSI ID7; this is the SCSI ID used by the integrated SCSI
controller.
7. Ensure each SCSI device is assigned a unique SCSI ID.
8. Verify all SCSI devices are all LVD (low voltage differential) SCSI and that no SE (single-ended
SCSI devices have been added). Note that SE devices will work on and LVD bus, but
performance will be degraded.
9. Verify the SCSI hard disk drive that loads the operating system is set to SCSI ID0.
10. Go into the SCSI Configuration Utility and set the transfer rate lower. The internal and external
SCSI subsystems are typically LVD and will be set to default at the maximum 80 MB/sec. If the
SCSI system works at lower transfer rate, you may infer a connector problems. Try cleaning
and reseating the SCSI cable. Try another cable.
To change the transfer rate for a SCSI device:
A. Press <CTRL> and <C> keys when prompted to enter the SCSI utility.
B. Select the either the internal or external SCSI controller. The internal SCSI channel is
usually port 2000. Press <Enter>.
C. After the utility scans the channel, it will list SCSI devices detected. You may change the
transfer rate for a specific device by selecting it, or for the entire channel by changing the
controller. Make your selection and press <ENTER>.
D. Press <ENTER> on Sync Rate to select a new transfer rate.
E. Follow the prompts to save the new setting and exit the utility.