GNU bug report logs - #30773
parted doesn't thoroughly erase old signatures

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Anatoly Mayorov <mt45 <at> yandex.ru>
To: bug-parted <at> gnu.org
Subject: parted doesn't thoroughly erase old signatures
Date: Sun, 11 Mar 2018 21:46:24 +0300

[Message part 1 (text/plain, inline)]

Hi,

I installed TrueOS and it partitioned the whole disk as a zfs pool. Then, while installing Archlinux I used parted to create a new gpt table with fat32, ext4 and btrfs partitions. Archlinux worked well. But Gparted reported, that the whole disk still was formatted to ZFS. I reproduced the same scenario on a virtual machine - the same result.
It turned out that there remained signatures from ZFS.
Here is what blkid and wipes reported:

root <at> debian:~# blkid /dev/sda
/dev/sda: TYPE="zfs_member" PTUUID="f80e1ce2-028f-4124-bdef-ce5a61ad4e72" PTTYPE="gpt"

root <at> debian:~# wipefs /dev/sda
offset type
----------------------------------------------------------------
0x200 gpt [partition table]

0x7f000 zfs_member [filesystem]

I had to manually erase all old signatures with wipefs to make Gparted see my partitions.

I'm attaching a screenshot of the virtual machine where I reproduced the scenario.

[gparted-qemu.png (image/png, attachment)]

Message #8 received at 30773 <at> debbugs.gnu.org (full text, mbox):

From: "Brian C. Lane" <bcl <at> redhat.com>
To: Anatoly Mayorov <mt45 <at> yandex.ru>
Cc: 30773 <at> debbugs.gnu.org
Subject: Re: bug#30773: parted doesn't thoroughly erase old signatures
Date: Thu, 7 Jun 2018 08:23:00 -0700

On Sun, Mar 11, 2018 at 09:46:24PM +0300, Anatoly Mayorov wrote:
> Hi,
> 
> I installed TrueOS and it partitioned the whole disk as a zfs pool. Then, while installing Archlinux I used parted to create a new gpt table with fat32, ext4 and btrfs partitions. Archlinux worked well. But Gparted reported, that the whole disk still was formatted to ZFS. I reproduced the same scenario on a virtual machine - the same result.
> It turned out that there remained signatures from ZFS.
> Here is what blkid and wipes reported:
> 
> root <at> debian:~# blkid /dev/sda
> /dev/sda: TYPE="zfs_member" PTUUID="f80e1ce2-028f-4124-bdef-ce5a61ad4e72" PTTYPE="gpt"
> 
> root <at> debian:~# wipefs /dev/sda
> offset type
> ----------------------------------------------------------------
> 0x200 gpt [partition table]
> 
> 0x7f000 zfs_member [filesystem]
> 
> I had to manually erase all old signatures with wipefs to make Gparted see my partitions.
> 
> I'm attaching a screenshot of the virtual machine where I reproduced the scenario.

parted doesn't wipe signatures. Use something like wipefs for that :)

This can also be a problem with RAID and LVM and recreating partitions with the
same sizes, you'll sometimes see old ones show up. So when re-using a
disk it's best to also wipefs it first.

-- 
Brian C. Lane (PST8PDT)

Message #11 received at 30773 <at> debbugs.gnu.org (full text, mbox):

From: Phillip Susi <psusi <at> ubuntu.com>
To: "Brian C. Lane" <bcl <at> redhat.com>, Anatoly Mayorov <mt45 <at> yandex.ru>
Cc: 30773 <at> debbugs.gnu.org
Subject: Re: bug#30773: parted doesn't thoroughly erase old signatures
Date: Mon, 18 Jun 2018 12:29:12 -0400

[Message part 1 (text/plain, inline)]

On 6/7/2018 11:23 AM, Brian C. Lane wrote:
> parted doesn't wipe signatures. Use something like wipefs for that :)

Sure it does; see ped_disk_clobber().  It wipes the first and last 8k of
the disk, which gets most signatures, but I'm guessing ZFS is not in
that range.  LVM is another oddly placed one iirc.

[signature.asc (application/pgp-signature, attachment)]

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