HP A6829A PCI Dual Channel Ultra160 SCSI Host Bus Adapter Service and User Guide (May 2003)

Troubleshooting
Domain Validation
Chapter 3 85
• Path width errors (for example, a Narrow cable used with a Wide
SCSI device)
• Damaged or marginal transceivers
• Excessive cross talk
• Excessive system noise
When Domain Validation determines that communication with the
target device is not possible at the maximum data transfer rate
supported by the HBA (Ultra160), it writes the following warning
message to the /var/adm/syslog.log file:
SCSI:Ultra160 SCSI Adapter at hw_path : fallback occurred for
target
target_ID . Possible causes are improper termination,
improper cabling, or malfunctioning hardware. Verify the
hardware at the next opportunity.
Later, it “falls back” (lowers the transfer rate and bus width) by one level,
according to Table 3-1 below.