How to safely remove rest of GTP?

[Rodney W. Grimes]

> On 31.01.2017 18:43, Rodney W. Grimes wrote:
> > ... much deleted ...
> >>
> >>> It is impossible to have a corrupted GPT and some
> >>> other type of partition table in the same time.
> >
> > I believe that statement is in error.
> > dd if=/boot/boot0 of=/dev/ada0
> > Would not that lead to this very situation if done
> > to a GPT parted disk drive?
> 
> No, it will not lead to this situation.
> /boot/boot0 is similar to /boot/mbr in the example, and with /dev/ada0 
> all will behaves like with /dev/md0.

Well if that is the case then the GPT backup copy is... well useless as
I just clobbered the MBR of a drive and now gpart is gona just take that
as fine and dandy?

Doesnt that defeat the purpose of the backup GPT?


> >> Maybe when only using FreeBSD and gpart, but I'm pretty sure I've seen
> >> forum users who have tried some crappy other formatting tool and have
> >> overwritten the primary GPT with a valid MBR and left the secondary GPT
> >> untouched.  This only becomes obvious when they bring the disk back to a
> >> FreeBSD system.
> >
> > As almost all MBR tools are un aware of GPT so well not do anything to
> > destroy the secondary GPT, so this is infact very likely to occur.
> 
> Please, give me some working example, when or where you have a problem, 
> and not some theoretical, based on previous negative experience or memories.

Next time I see one I well be sure to preserve it, but I have seen problems
with bad interactions between GPT and MBR.

-- 
Rod Grimes                                                 rgrimes at freebsd.org