Re: Destroy GPT partition scheme absolutely, how?

From: Allan Jude <>
Date: Wed, 28 Sep 2016 15:02:46 -0400
On 2016-09-27 01:58, Warner Losh wrote:
> On Mon, Sep 26, 2016 at 11:06 PM, O'Connor, Daniel <> wrote:
>>> On 27 Sep 2016, at 14:28, Warner Losh <> wrote:
>>> dd of 2MB of zeros to the start and end of the disk. That will destroy
>>> pretty much everything. For SSDs, sometimes you can do the same with
>>> TRIMs only faster (other times they are slower or unreliable).
>> Yeah, but it would be nicer to not have to know that particular magic incarnation :)
> Disk formatting has always been 3 parts magic, 2 parts luck and 1 part skill :)
> It doesn't fit nicely into geom because metadata can live elsewhere.
> I forgot to add the caveat not to try this on a disk that is part of a
> RAID volume.
> Warner
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I wonder if this issue is related at all to the new 'auto resize' gpart
bits. That leaves the 'uncommitted' transaction pending, and may require
a 'gpart undo' before the other commands will work correctly.

I wonder if something like 'zpool labelclear', but for gpart would be
useful, that just nukes the first and last few MB of the disk. I know in
the installer we jump through a number of hoops to try to clear out old
stuff, and having one command would be better.

Allan Jude

Received on Wed Sep 28 2016 - 17:02:52 UTC

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