Technical data

16 Troubleshooting
If an Error is Detected
If there are any question marks (?) on the SCSI controller’s status line,
the SCSI controller is probably faulty and must be replaced.
If there are any question marks on a drive’s status line, the problem could
be in either the drive, the SCSI bus cabling, the SCSI bus terminator,
or the SCSI controller. For example, an error that is listed in the drive’s
code may be a data transfer error and does not isolate the problem to the
device itself; it may still be in the SCSI controller.