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

Troubleshooting
Domain Validation
Chapter 384
Domain Validation
Domain Validation provides a way to automatically detect, and if
necessary, compensate for hardware that is not performing to the
optimal level. It does this by reducing the data transfer rate and bus
width. This allows you to have data integrity even if data transfers
cannot occur at the maximum data transfer rate supported by the HBA.
If Domain Validation does reduce the rate and bus width, a message is
generated so that you can correct the problem.
Domain Validation is automatically enabled for all SCSI devices on the
bus, as long as you have set the HBA’s maximum data transfer rate to its
maximum speed (160 MB/s for the A6829A). See “Maximum Data
Transfer Rate” on page 45 for more information on setting the HBA’s
transfer rate.
TIP If necessary, you can disable Domain Validation—if you want to do
diagnostics, for example—by lowering the transfer rate to less than
Ultra160 through the commands in the BCH menus (see “Maximum
Data Transfer Rate” on page 45).
Domain Validation runs each time the initiator device and target device
negotiate the transfer rate and bus width. A few things that can cause
this are as follows:
• A protocol violation or some other exception condition occurs on the
SCSI bus.
• A SCSI device is powered on and then I/O occurs to that device.
Things that Domain Validation might detect are as follows:
• Incorrect or improper SCSI bus termination (for example, a missing
or bad terminator or an incorrect auto termination setting)
• Incorrect hardware configuration
• Cables with the wrong impedance
• Major cable errors (for example, a broken wire within a cable)
• SCSI device spacing problems