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Re: How to make btrfs forget a disk?

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Victor Sudakov wrote:
> 
> btrfs thinks that /dev/nvme1n1 has a btrfs:
> 
> # btrfs filesystem show
> Label: none  uuid: 3414ae53-f3d4-43ea-bb88-ffefc9bc86f6
>         Total devices 1 FS bytes used 1.05TiB
>         devid    1 size 2.00TiB used 1.33TiB path /dev/nvme0n1
> 
> Label: none  uuid: 38f74bc8-465d-4866-8ec1-3a144741012c
>         Total devices 1 FS bytes used 831.16GiB
>         devid    1 size 3.00TiB used 1.48TiB path /dev/nvme1n1
> 
> The problem is that /dev/nvme1n1 is being used for ZFS now, and there is
> currently no btrfs thereon. However, there is a btrfs label or something
> stuck somewhere, how can I clear it?
> 
> I tried to unload/load the btrfs kernel module but it did not help. 
> It's somewhere on disk, but where?

Found some hints and recipes in
https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#How_to_clean_up_old_superblock_.3F
So the culprit probably *was* the btrfs superblock. Deloptes you were
right.

It's interesting however that "zpool create" created a GPT (which I did
not want), but did not erase a superblock from a previous filesystem.

A lesson? Always dd the first several MB of a disk with zeroes when
changing partitioning schemes, whole disk filesystems etc.

-- 
Victor Sudakov VAS4-RIPE
http://vas.tomsk.ru/
2:5005/49@fidonet

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Thread

How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 03:40 +0100
  Re: How to make btrfs forget a disk? David <bouncingcats@gmail.com> - 2021-03-12 04:20 +0100
    Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 04:50 +0100
      Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 06:20 +0100
        Re: How to make btrfs forget a disk? deloptes <deloptes@gmail.com> - 2021-03-12 08:00 +0100
          Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 10:20 +0100
            Re: How to make btrfs forget a disk? David <bouncingcats@gmail.com> - 2021-03-12 10:40 +0100
              Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 11:00 +0100
            Re: How to make btrfs forget a disk? deloptes <deloptes@gmail.com> - 2021-03-12 12:10 +0100
        Re: How to make btrfs forget a disk? Anssi Saari <as@sci.fi> - 2021-03-12 09:20 +0100
          Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 10:30 +0100
      Re: How to make btrfs forget a disk? David <bouncingcats@gmail.com> - 2021-03-12 10:30 +0100
        Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-12 11:10 +0100
  Re: How to make btrfs forget a disk? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-03-12 17:10 +0100
    Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-14 05:00 +0100
      Re: How to make btrfs forget a disk? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-03-14 10:50 +0100
        Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-14 11:40 +0100
          Re: How to make btrfs forget a disk? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-03-14 12:20 +0100
            Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-15 04:50 +0100
  Re: How to make btrfs forget a disk? Victor Sudakov <vas@sibptus.ru> - 2021-03-16 03:20 +0100

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