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Re: BTRFS and debian

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On 07/14/18 02:04, Pascal Hambourg wrote:
> 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.

Okay.


>>> 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. 

Fortunately, I only need 3 partitions on my system drives.  I have 
always used primary partitions.


> Yet 
> another reason to not use logical partitions and prefer GPT if you need 
> more than 4 partitions.

GPT is nice; I use it when I want a 2+ TB partition (such as my backup/ 
archive/ image drives).  But I have several older computers, so I prefer 
solutions that work with BIOS/MBR.

David

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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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