On Thu, Mar 02, 2017 at 09:06:52PM -0500, fred roller wrote:
> On Thu, Mar 2, 2017 at 8:36 PM, Robert Moskowitz <rgm@xxxxxxxxxxxxxxx>
> wrote:
>
> > dd if=/dev/sdb of=os.img bs=1M count=3210
> >
>
> I would recommend bs=512 to keep the block sizes the same though not a huge
> diff just seems to be happier for some reason and add status=progress if
> you would like to monitor how it is doing. Seems the command you have
> should work otherwise.
The dd blocksize has nothing to do with the disk sector size.
the disk sector size is the number of bytes in a minimal read/write
operation (because the physical drive can't manipulate anything smaller).
the dd blocksize is merely the number of bytes read/written in a
single read/write operation. (or not bytes, but K, or Kb, or other
depending on the options you use.)
It makes sense for the bs option in dd to be a multiple of the actual
disk block/sector size, but isn't even required. if you did dd with a
block size of, e.g., 27, it would still work, it'd just be stupidly slow.
Fred
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