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

Troubleshooting
Domain Validation
Chapter 3 87
(shown earlier in this section). If the problem was fixed properly and
Domain Validation is at the correct level, you will not see any new
warning messages.
As an example, if the parameters originally negotiated during the
normal SCSI initiator/target communications are equivalent to
Ultra160, but Domain Validation determines that the SCSI bus or the
target cannot support that data transfer rate, Domain Validation falls
back to Ultra2 Wide. Then, Domain Validation repeats its test. If the bus
or target still cannot support the transfer rate, Domain Validation falls
back another level, to Ultra2 Narrow. As long as failures occur, fallback
continues, one level at a time, until the last level in Table 3-1
(Asynchronous) is reached. (Note that a “fallback” warning
message—shown earlier in this section—is not generated each time
Domain Validation falls back a level, but only when it successfully settles
at a level.) If the last level is reached and a failure still occurs, the
following message is written to the /var/adm/syslog.log file:
SCSI:Ultra160 SCSI Adapter at hw_path : Error: The domain
validation test for target
target_ID determined that
communication may not be possible to this target. Verify the
hardware at the next opportunity.
To be able to restore communication to the target hardware, you must fix
the problem with the target, power cycle (power off and then power on)
the target, and then run ioscan without the -k option to restart Domain
Validation and renegotiate the parameters for that target. Next, you
need to check /var/adm/syslog.log for any new “fallback” warning
messages. The lack of new “fallback” messages means you successfully
fixed the problem, and the data transfer rate and bus width are at the
correct levels.
Note that when a Domain Validation test succeeds, no message is written
to the /var/adm/syslog.log file. The reason is that this would generate
a large volume of messages, especially on a system that is used heavily.
Not only would this make the file very large, but the more important
warning and error messages would not be easy to see.
In addition, a SCSI selection timeout—when a target device does not
respond to selection within a certain length of time—will terminate a
Domain Validation test on a target, and the target will be considered to
be non-existent. This is so that a bus scan or system boot will not be
extended by Domain Validation waiting several times for a target that
does not exist.