It turns out to be the problem of my media (CDR), the upgrade from 5.1 to
5.1A worked with the original 5.1A CD.  Thanks for 
Dr. Thomas Blinn, Zoltan Horvath, and Debra LaGattuta for suggestions.
The original question:
> 
> Dear Managers,
> 
> Today, I have successfully upgraded my system (DS20E) from 4.0G to 5.1.
> But I failed to the the same thing from 5.1 to 5.1A.  I have used the
> same procedure from 4.0G to 5.1.
> 
> boot to single user mode
> 
> boot -flags s dka0
> /sbin/lsmbstartup
> /sbin/bcheckrc
> /sbin/installupdate /dev/disk/cdrom0c
> 
> The system panicked and restart to 5.1 again.
> 
> For 5.x, do I need to use a different procedure to upgrade?
> Thank you for your assistance.
> 
> Regards
> --
> Zhi-Wei Lu
> CIPIC (Center for Image Processing and Integrated Computing)
> UC Davis                Phone:  (530)-752-0494
> Davis, CA 95616         Fax:    (530)-752-8894
-- 
Zhi-Wei Lu 		
CIPIC (Center for Image Processing and Integrated Computing)
UC Davis 	  	Phone:	(530)-752-0494
Davis, CA 95616		Fax:   	(530)-752-8894
Received on Wed Jan 23 2002 - 23:32:31 NZDT