On Fri, 22 Feb 2008, James Hartley wrote:

> On Fri, Feb 22, 2008 at 1:21 AM, kim <[EMAIL PROTECTED]> wrote:
> >  Just out of interest, what happens when you delete the 'c' partition? I
> >  understood it deleted the drive spec but is this irreversible? can you
> >  low level format the drive or repopulate the information some other way,
> >  or with some other format software?
> 
> The definitive answer to your question is to try & see.  Although I
> have been curious about this at times, I haven't been so curious to
> invest the time to experiment.
> 
> As for conjecture, I would doubt that there is any physical harm in
> deleting *all* partitions, but I doubt if there are any tools which
> would reverse the result.  I suspect one would end up having to
> reinstall, but again, this is only a guess.
> 
> Jim

No, if you know the partition data, you can restore it, whether we are
talking about fdisk partitions or disklabel partitions.

Usually "having to reinstall" means "having to run a reinstall [sic]
script to get to some canned command that does what I want".  Sometimes
it's just convenient.

In the "ancient days" there were no installation scripts.  One
disklabeled, then one copied from some medium or other (tape, often)
with dd.   There were bootstrapping thingies to get this process
going, which "back then" resided in the ROM of the machine [not
peecees].  Sun still makes machines like this.  The discovery that
a peecee doesn't have bootstrapping code and utilities in its
ROM is the first of many disappointments one discovers when
moving to them from better architectures.  This was a cost-saving
measure.  The empty sockets for the ROM were once prominent features
of peecee mobos.

It's actually instructive to look at the very nicely written
shell script(s) associated with OpenBSD's installation process.
You can see how *little* is really involved in installation, and
realize that you could do this completely by hand.  It's actually
"trick-free", very straightforward.  fdisk, disklabel, tar, makedev
and some "extras" that amount to editing some network config and
setting a timezone -- stuff you could do after the first boot,
actually.

So, if you know the disklabel, you can very likely totally
skunk it -- the machine would probably continue to run and
access the files in the "deleted" partitions, due to the kernel
having its own copy.  You could then, working from a paper note
of the disklabel, re-enter it, write it back to the disk, and
no one could tell.  Same for fdisk.  Same for bootblocks.
I even bet this can be done while running multiuser.

Notice in disklabel's man page that a certain amount of space
is spent on how to make a copy to a disk file of a disklabel
and how to restore one from disk.

If there's any real demand for this, I've got a couple of
throw-away machines to try it on.

Dave
-- 
   The president of the United States is the commander-in-chief of
   the armed forces.  He is not the commander-in-chief of the
   government, nor is he the commander-in-chief of the country.
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