Re: Issue writing image to disk via dd
On Wed, Apr 13, 2011, at 14:33:34 +1000, Scott Ferguson wrote:
> It's possible the script uses ddrescue instead of dd to create the
> image
> - though I still don't understand why that would make a difference.
I could be wrong, but from looking at the script a bit it looks like dd
is used to create the image like this:
dd of=tmp/disk.img if=/dev/zero count=30720 bs=1k
Then the image is configured as a virtual device where things
like bsdlabel/newfs are done to it, and then mounted for files to be
added that way.
> Which OS did you run the image creation script from?
FreeBSD 8.2.
> I'd expect a x86 bs to use 512 bytes, rather than 1M (I have a hazy
> memory about 512 and larger multiples being valid values...) - but
> partition type and file-system (5xbsd?) being BSD probably changes
> things.
I was using 1M as that is what the documentation for this process
suggests, though trying with 512 bytes or not specifying a bs doesn't
change things either way.
> Which would support your theory that it's due to a difference in dd
> between to two distros...
>
> I'm assuming the message displayed by dd when the write is finished,
> is identical in both cases (Debian and ArchLinux)?
Yes, the dd output from both Debian and Arch is identical in terms of
records in/out, bytes written, etc.
> Sorry I can't provide an answer. Any chance you could post the script
> you used to create the image, or a link to it (I suspect it will
> answer the questions)??
Sure, the script link is below, though it is a bit more complex than a
single shell script. I realize what I'm trying to do here is probably
off topic for the Debian list, but because the same process is
having quite a different result on Debian vs another Linux distro I
hope it is OK to discuss it here.
http://mfsbsd.vx.sk/release/mfsbsd-1.1.tar.gz
> Curiouser and curiouser....
>
> Cheers
Thanks for your interest and ideas!
-Mark
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