If you are unsuccessful in obtaining a generic U320 firmware from Dell or Seagate, you may want to ask a SCSI Guru, that you may know, the actual SCSI mode page setting that governs U160/U320 interface.
SCSI Toolbox Software allows you to ferret through all the mode pages stored on SCSI firmware; in addition the software provides diagnostic, and benchmark tools.
For individual use, the software is expensive, targeted mainly for large corporate use, harddrive labs, or used by some Mfg. during field diagnostic use. You can request a 14 day, fully functional, demo via the website.
If you can determine the mode page setting restriction for U160 interface, usually located in Operating Definition Page, you can change the driveâ€™s definition to interface to SCSI-3 or SCSI-4 protocol; U320 depending on the Mfg.
The software, I believe, allows you to make the mode page change temporary, for testing purpose, without immediately hardcoding the change into the driveâ€™s firmware:
Locate the definition page setting, and change the mode page parameter, and use the temporary change option; as a sensible precaution.
Re-boot, without powering down the drive, test for U320 functionality, if satisfied you can access the same mode page again, and make the change permanent.
If the mode page change did not work, usually the HBA controller is unable to interrogate the drive, or the drive times-out, then power down the drive, during the next boot-up cycle any temporary mode page change are reset back to the driveâ€™s original firmware parameters.
Again, you should have extensive knowledge of SCSI internal commands, or contact a SCSI Guru if you know one; to make sure the correct SCSI mode page setting is accessed.
This software is targeted for seasoned SCSI experts; no safety nets are in place, except for the temporary option.
There is one caveat: some OEM firmwares are compiled to disallow high level mode page changes, even with the referenced software: IBM is one of them.