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Re: BTRFS and debian

From Pascal Hambourg <pascal@plouf.fr.eu.org>
Newsgroups linux.debian.user
Subject Re: BTRFS and debian
Date 2018-07-14 11:10 +0200
Message-ID <wboIV-7U7-1@gated-at.bofh.it> (permalink)
References (3 earlier) <waA9s-3fE-7@gated-at.bofh.it> <waCEh-4yC-3@gated-at.bofh.it> <waUUx-6QJ-5@gated-at.bofh.it> <wbeTf-1Ps-1@gated-at.bofh.it> <wbh4J-36K-1@gated-at.bofh.it>
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Le 14/07/2018 à 02:49, David Christensen a écrit :
> # file -s /dev/sda1
> /dev/sda1: BTRFS Filesystem label "po_boot", sectorsize 4096, nodesize 
> 16384, leafsize 16384, UUID=6ff0dd1d-8d46-454b-bb35-a09afc47145a, 
> 65490944/999292928 bytes used, 1 devices
> 
> 2018-07-13 17:39:51 root@po ~
> # file -s /dev/sda2
> /dev/sda2: data
> 
> 2018-07-13 17:39:59 root@po ~
> # file -s /dev/sda3
> /dev/sda3: LUKS encrypted file, ver 1 [aes, xts-plain64, sha256] UUID: 
> 0152d2e2-4cfb-42c4-a121-6fb832962e47
> 
> The output for /dev/sda2 is not very informative (e.g. clues that it has 
> dm-crypt, random key, and swap).

As expected. /dev/sda2 contains raw encrypted data which appear as 
random data. It is the purpose of encryption that one cannot see the 
real contents.

>> Beware that unlike a UUID or LABEL, a PARTUUID or PARTLABEL is stored 
>> in the partition table, not in the partition data.
>> Also note that a DOS partition table entry does not contain a UUID nor 
>> LABEL, and the PARTUUID is artificially built by combining the 32-bit 
>> "disk identifier" field in the MBR and the partition number. So if the 
>> partition number or the disk identifier changes, the PARTUUID changes.
>>
>> In short :
>> - if you move the disk contents (including the partition table) to 
>> another disk, the PARTUUID is preserved ;
>> - if you move the partition contents to another partition, the 
>> PARTUUID is not preserved.
> 
> Thanks for the warning.  My typical use-case is to move the entire 
> system drive image between various 16+ GB devices, so PARTUUID should work.

I forgot to mention another case, although you are not concerned :

- logical partitions numbers and synthetic PARTUUIDs may change when 
creating or deleting another logical partition on the same disk. Yet 
another reason to not use logical partitions and prefer GPT if you need 
more than 4 partitions.

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BTRFS and debian Ge <gpdsbe@mailbox.org> - 2018-07-09 20:20 +0200
  Re: BTRFS and debian Matthew Crews <mailinglists@mattcrews.com> - 2018-07-09 21:40 +0200
    Re: BTRFS and debian Ulf Volmer <u.volmer@u-v.de> - 2018-07-09 22:00 +0200
      Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-09 23:00 +0200
        Re: BTRFS and debian Ulf Volmer <u.volmer@u-v.de> - 2018-07-09 23:10 +0200
      Re: BTRFS and debian Matthew Crews <mailinglists@mattcrews.com> - 2018-07-09 23:40 +0200
  Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-10 05:40 +0200
    Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-11 20:40 +0200
      Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-12 05:10 +0200
        Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-12 07:50 +0200
          Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-13 03:20 +0200
            Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-14 00:40 +0200
              Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-14 03:00 +0200
                Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-14 11:10 +0200
                Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-14 21:40 +0200
                Re: BTRFS and debian Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-07-14 23:10 +0200
            Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-14 01:40 +0200
    Re: BTRFS and debian David Wright <deblis@lionunicorn.co.uk> - 2018-07-12 20:00 +0200
      Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-13 05:00 +0200
        Re: BTRFS and debian Dan Ritter <dsr@randomstring.org> - 2018-07-13 12:00 +0200
          Re: BTRFS and debian <tomas@tuxteam.de> - 2018-07-13 12:30 +0200
          Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-14 03:10 +0200
        Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-14 01:40 +0200
          Re: BTRFS and debian David Christensen <dpchrist@holgerdanske.com> - 2018-07-14 03:10 +0200
            Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-14 12:00 +0200
              Re: BTRFS and debian Reco <recoverym4n@gmail.com> - 2018-07-14 12:30 +0200
                Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-14 12:40 +0200
              Wrapping lines, was Re: BTRFS and debian David Wright <deblis@lionunicorn.co.uk> - 2018-07-15 05:20 +0200
                Re: Wrapping lines, was Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-15 05:30 +0200
                Re: Wrapping lines, was Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-15 12:30 +0200
        Re: BTRFS and debian Zenaan Harkness <zenaan@freedbms.net> - 2018-07-14 11:40 +0200

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