How to restore a USB drive converted to bootable

Polytropon freebsd at
Sat May 2 21:38:59 UTC 2015

On Sat, 02 May 2015 09:20:09 -0453, William A. Mahaffey III wrote:
> On 05/02/15 09:06, Lowell Gilbert wrote:
> > "William A. Mahaffey III" <wam at> writes:
> >
> >> I am about to do some OS installs (NetBSD & OpenBSD, as it happens) on
> >> boxen under construction. I would also like to use UBCD on a flash
> >> drive to memcheck those boxen prior to installation. If I prep a USB
> >> thumb drive as either a bootable UBCD drive or an over-the-WWW
> >> installer, I wipe out the drive for its original use. Is there a way
> >> to restore the drive back to its original functionality if I wanted to
> > Is "wipe the drive and reformat" what you need to hear, or do you have
> > more requirements that you haven't made clear?
> >
> Wipe & reformat, preferably from CLI under FBSD 9.3R-p13 for 
> convenience, is what I'm after. Clearly creating a bootable UBCD or 
> installer will wipe out whatever was
> there before, so I just want to get back to 'virgin' USB drive.

In that case, the command

	# dd if=/dev/zero of=/dev/da0 bs=1m count=1

should be fine. If there is any offending GPT metadata located
at the end of the USB drive, estimate the size and also erase
the last few MBs (use skip= to do so). There is no need to
actually zero out the _whole_ drive.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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