On Oct 17, 10:51pm, Arne Henrik Juul wrote:
> The read-only file system error is because of disklabel protection.
> I would guess that's also the reason for the silent failure when
> using the /dev/rz1c device as well.  To actually get the bootblocks
> *written* to disk I had to write a C program using the DIOCWLABEL
> ioctl, and /dev/rrz1c.

  Disklabel can enable writing of the label area - but that enable is
only as long as the partition is open.  Mounting the partition is
sufficient to keep the label area write enabled, but this won't work if
there isn't a mountable filesystem on the disk.  A cute trick I've used
is to do a dd if=/dev/rrz1c of=/dev/null and then suspend that process. 
That will leave the partition open and disklabel can then be used to
write enable the label area and leave it enabled.  Then you can run
another dd to copy the disk image.


-- 
Michael L. Hitch			mhitch@montana.edu
Computer Consultant
Information Technology Center
Montana State University	Bozeman, MT	USA