using dd to backup entire hard drive

On Fri, 2003-01-31 at 17:51, Bob Holtzman wrote:
> On 30 Jan 2003, Craig White wrote:
>
> > As a follow up, being the impatient person that I am, I just went ahead
> > and did it.
> >
> > dd if=/dev/hda of=/dev/hdd bs=512
> >
> > and it worked fine (target drive was slave on secondary controller,
> > hence /dev/hdd
>
> Would it work to use /dev/ht0 instead of /dev/hdd to dump to tape. If
> so, do you swap /dev/hda with /dev/ht0 to recover data?
>
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I think the block sizes are different.

See - man dd or probably info dd, on RH 8 there was a bit of an
explanation. I had to wing it myself when no one stepped up to answer
the question right away

Which actually brings up a point. I had a problem with the computer that
I was using (an HP Brio - few years old...P III /500)

When I had two linux drives installed hda & hdd for example, I would get
an error if I tried to boot normally. It would not mount /usr and
probably some other file systems. The only way I could get things to
work was to boot from CD, clone the disk (using dd) shutdown, and then
disconnect the extra drive. I have done this several times on other
systems without incident...allows me to copy config files and such. On
two of these machines, I had the same problem. Any one want to guess
why?

Craig