Date: Fri, 26 Jan 1996 13:26:01 +1000 (EST) From: Gary Roberts <garyr@ajax.che.curtin.edu.au> To: stesin@elvisti.kiev.ua (Andrew V. Stesin) Cc: gfoster@gfoster.com, doc@FreeBSD.ORG Subject: Re: Frustrated....doc@freebsd.org Message-ID: <199601260326.NAA06133@ajax.che.curtin.edu.au> In-Reply-To: <199601251556.RAA00921@office.elvisti.kiev.ua> from "Andrew V. Stesin" at Jan 25, 96 05:56:17 pm
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Andrew V. Stesin writes:
> What's interesting: while sd1 was a fresh-formatted disk,
> dd worked Ok, I made an initial copy of rsd0c to rsd1c
> easily (fast!). But now I can't dd my rsd0a to rsd1a -- dd fails
> telling me that rsd1a is read-only file system. ???
> rsd0e to rsd1e works fine! A day of beating and RTFMing
> with zero result. But this belongs to questions@freebsd.org,
> I'll ask there later... or learn how to "dump (1)", at last :)
I believe I know the answer to your problem. The rsd1a is special in
that the boot block and disklabel are on the front of it. With a
freshly formatted disk, the first time you do the dd to rsd1a, there is
no boot block or disklabel to overwrite, so it works. When you try to
do it a second time however, you are attempting to overwrite the
boot block and disklabel, so dd complains. The workaround is to use:
dd if=/dev/rsd0a of=/dev/rsd1a bs=16b skip=1
^^^^^^
whick will leave the boot block and disklabel alone. I only know this
because Rod Grimes told me once about it and I did use it successfully
with making clone copies of IDE disks, fully configured. Sure beats
doing a full installation and configuration for second and subsequent
systems that are to be essentially identical to the first.
As a disclaimer :-), I did this about 12-18 months ago and it worked
then on IDE disks (rwd0a -> rwd1a). I have no recent experience or
knowledge of any changes (to the slice code for example) which may
affect the present viability of the technique. The problem you
describe is identical to what I was experiencing, however.
Good luck with it.
Cheers,
--
Gary Roberts (garyr@wcs.uq.edu.au) (Ph +617 3844 0400 Fax +617 3844 0444)
4th Floor, South Bank House, 234 Grey St, South Bank QLD 4101 Australia.
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