HELP......I can't boot

[Farooq Butt]

Hi there folks : 

I am having a strange problem.  I have a 3/480S hooked up to 5 CDC 1.2 Gig
Sabers.  There are 2 disks (xd0 & xd1 on units 0 & 1) on the first 753
ctrlr.  On the second ctrlr I have 3 disks (xd4, xd5 and xd6 on units 0,1
& 2).  I have a root filesystem on /dev/xd0a and that works just great.
Out of sheer madness, I decided to make a "twin" root disk on xd6.  I did
"dd if=/dev/rxd0a of=/dev/rxd6a ......  etc.  etc...." for each partition
on the root disk until xd6 looked like and EXACT copy of xd1.  I then
fscked all the xd6 partitions until fsck was happy, did an "installboot
/boot bootxd /dev/rxd6a" and thought that all would be great.  I then
fasthalted the machine and tried to boot from the prom.  I tried ">b
xd(1,6,0)" that died on a label read error (error #3).  I then tried ">b
xd(1,2,0)" (since xd6 is the #2 disk on ctrlr 1) and that crapped out with
a BUS ERROR ! What am I doing wrong.  What is the best way to get a twin
root disk ???????  The filesystems on the xd6 "look" just fine; my PROM
just seems to hate to boot from anything but xd0. HELP ! 

Thanks in advance!
Farooq

PS: I *do* have swap allocated on the xd6 drive....