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  • Recent issue with /dev/disk/by-uuid

    From Rick Mangus@21:1/5 to All on Sat Oct 28 08:40:01 2023
    After a recent dist-upgrade, I failed to mount /boot when rebooting.
    Further investigation shows that /dev/disk/by-path has an entry for my
    /boot as /dev/sda (rather than sda1). Updating to use the by-id in
    /etc/fstab solves the problem, but I'm curious what changed and if
    this is a known issue. I would guess that this is an issue with
    changes in either udev or the kernel.

    The partition table is a Sun disk label, which means that /dev/sda1
    starts at sector 0 and the filesystem header thus starts in the same
    place as if there were no partition table. I believe on my e450 that
    this is in fact required for the boot partition, so I don't know that
    there's an easy fix in the installer aside from defaulting to one of
    the by-id options.

    Copy/paste of relevant information below: ----------------------------------------------------------
    root@alexandria:~# grep boot /etc/fstab
    # /boot was on /dev/sda1 during installation #UUID=e952f794-4d8e-4bba-8c5a-851acdb5e886 /boot ext2
    defaults 0 2
    /dev/disk/by-id/wwn-0x5005076506c6bd8a-part1 /boot ext2 defaults 0 2 root@alexandria:~# ls -l /dev/disk/by-uuid/
    total 0
    lrwxrwxrwx 1 root root 10 Oct 27 18:26
    6194b363-9f57-401b-a3cb-ee4bc8895323 -> ../../sda2
    lrwxrwxrwx 1 root root 10 Oct 27 18:26
    704f946c-b8e8-4a00-9d18-c49b325cd7e3 -> ../../sda4
    lrwxrwxrwx 1 root root 9 Oct 27 18:26
    e952f794-4d8e-4bba-8c5a-851acdb5e886 -> ../../sda
    root@alexandria:~# blkid
    /dev/sda4: UUID="704f946c-b8e8-4a00-9d18-c49b325cd7e3" TYPE="swap"
    /dev/sda2: UUID="6194b363-9f57-401b-a3cb-ee4bc8895323"
    BLOCK_SIZE="4096" TYPE="ext4"
    /dev/sda3: UUID="e952f794-4d8e-4bba-8c5a-851acdb5e886"
    BLOCK_SIZE="1024" TYPE="ext2" PTTYPE="sun"
    /dev/sda1: UUID="e952f794-4d8e-4bba-8c5a-851acdb5e886"
    BLOCK_SIZE="1024" TYPE="ext2" PTTYPE="sun"
    root@alexandria:~# parted /dev/sda p
    Model: IBM DDYST1835SUN18G (scsi)
    Disk /dev/sda: 18.1GB
    Sector size (logical/physical): 512B/512B
    Partition Table: sun
    Disk Flags:

    Number Start End Size File system Flags
    1 0.00B 512MB 512MB ext2 boot
    2 512MB 17.1GB 16.6GB ext4
    4 17.1GB 18.1GB 1025MB linux-swap(v1)

    root@alexandria:~#
    ----------------------------------------------------------

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Engelhardt@21:1/5 to Rick Mangus on Sat Oct 28 10:00:01 2023
    On Saturday 2023-10-28 08:30, Rick Mangus wrote:

    The partition table is a Sun disk label, which means that /dev/sda1
    starts at sector 0

    (which it does not _have_ to)

    and the filesystem header thus starts in the same
    place as if there were no partition table.

    yeah, that kind of speaks for itself how the by-{uuid,id,label} link can shift between sda <-> sda1.

    I believe on my e450 that
    this is in fact required for the boot partition

    Not that I know of. It's pretty much like on x86, with sector 0
    containing a few boot bytes to load "something else", irrespective
    of a logical partitioning scheme superimposed on top.
    What I had with my T1000 was: https://inai.de/2006/03/30

    [if] there's an easy fix in the installer aside from defaulting to
    one of the by-id options.

    You could move the disk blocks down the line (intricate dd_rescue
    operations) and modify the partition table to match it,
    moving /boot so it does not start at 0.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)