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  • [gentoo-user] Help!!! My system won't boot. (?lvm?) :-(

    From Alan Mackenzie@21:1/5 to All on Wed Jan 11 21:00:01 2023
    Hello, Gentoo.

    My system isn't booting. In particular, most of the SSD partitions
    won't mount, because they are not under /dev any more. The root
    partition, /dev/md125 mounts, but that is all.

    These partitions are lvm partitions under RAID-1 (software RAID). They
    simply fail to appear in /dev/mapper on boot up. (I don't remember the
    exact error message, here).

    I've managed to bring my system up using a Rescue-DVD followed by
    chroot. This shows that the partions on the SSD are basically
    undamaged.

    I strongly suspect that my emerge update from last night is to blame.
    There, lvm2-2.03.17-r1 was reinstalled after other packages
    (dependencies) were updated. The order of these packages, taken from /var/log/emerge.log was:

    1. dev-libs/mpfr-4.1.1_p1
    2. dev-lang/mujs-1.3.2
    3. sys-apps/util-linux-2.38.1
    4. sys-apps/systemd-utils-251.10
    5. dev-python/installer-0.6.0
    6. app-text/lib-paper-2.0.4
    7. app-misc/ca-certificates-20211016.3.86
    8. sys-fs/lvm2-2.03.17-r1

    .. There were a few more packages after that, a total of 23. If any of
    these is relevant, then it is surely 3. or 4. lvm2 itself was merely
    rebuilt.

    I've had a quick scan of the gentoo bugzilla, but not found anything
    relevant there.

    Please help me get my system booting again!

    Thanks!

    --
    Alan Mackenzie (Nuremberg, Germany).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Alan J. Wylie@21:1/5 to Alan Mackenzie on Wed Jan 11 21:20:02 2023
    Alan Mackenzie <[email protected]> writes:

    My system isn't booting. In particular, most of the SSD partitions
    won't mount, because they are not under /dev any more. The root
    partition, /dev/md125 mounts, but that is all.

    These partitions are lvm partitions under RAID-1 (software RAID). They simply fail to appear in /dev/mapper on boot up.

    I've managed to bring my system up using a Rescue-DVD followed by
    chroot. This shows that the partions on the SSD are basically
    undamaged.

    I strongly suspect that my emerge update from last night is to blame.

    It was.

    Been there, done that myself.

    Mount your filesystems from the rescue boot and chroot into them.

    Re-emerge lvm2 with the "lvm" flag enabled.

    See https://www.gentoo.org/support/news-items/2022-11-19-lvm2-default-USE-flags.html

    Some of these commands (or similar) in the rescue boot might be helpful:

    mkdir -p /mnt/{usr,var,home,work,boot,dev,sys,proc}

    mount /dev/mapper/vg0-root /mnt
    mount /dev/mapper/vg0-usr /mnt/usr
    mount /dev/mapper/vg0-var /mnt/var
    mount /dev/mapper/vg1-home /mnt/home
    mount /dev/mapper/vg1-work /mnt/work

    mount /dev/sda1 /mnt/boot

    mount -o bind /dev /mnt/dev
    mount -o bind /dev/pts /mnt/dev/pts
    mount -o bind /dev/shm /mnt/dev/shm
    mount -o bind /sys /mnt/sys
    mount -o bind /proc /mnt/proc

    PATH=/bin:/sbin:/usr/bin:/usr/sbin \
    SHELL=/bin/bash \
    chroot /mnt

    --
    Alan J. Wylie https://www.wylie.me.uk/

    Dance like no-one's watching. / Encrypt like everyone is.
    Security is inversely proportional to convenience

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Alan Mackenzie@21:1/5 to Alan J. Wylie on Thu Jan 12 11:40:01 2023
    Hello, Alan.

    On Wed, Jan 11, 2023 at 20:16:07 +0000, Alan J. Wylie wrote:
    Alan Mackenzie <[email protected]> writes:

    My system isn't booting. In particular, most of the SSD partitions
    won't mount, because they are not under /dev any more. The root
    partition, /dev/md125 mounts, but that is all.

    These partitions are lvm partitions under RAID-1 (software RAID). They simply fail to appear in /dev/mapper on boot up.

    I've managed to bring my system up using a Rescue-DVD followed by
    chroot. This shows that the partions on the SSD are basically
    undamaged.

    I strongly suspect that my emerge update from last night is to blame.

    It was.

    Been there, done that myself.

    Mount your filesystems from the rescue boot and chroot into them.

    Re-emerge lvm2 with the "lvm" flag enabled.

    Many thanks, indeed! That was the cause of my problem, and re-emerging
    lvm2 with that USE flag set solved it completely.

    See https://www.gentoo.org/support/news-items/2022-11-19-lvm2-default-USE-flags.html

    Yes. There was even a news item about it back in November. I've read
    it again, and it seems too vague to me. For example, it says:

    If you use LVM2 for any partitions, or if you use tools like
    'lvchange', you should enable USE=lvm.

    , without saying in detail anywhere what it means to "use" LVM2. I
    wasn't aware of "using" LVM2 when I read that news item, so I just
    carried on, blithely unaware of the coming catastrophe. ;-)

    Still, it's OK, now.

    Some of these commands (or similar) in the rescue boot might be helpful:

    mkdir -p /mnt/{usr,var,home,work,boot,dev,sys,proc}

    mount /dev/mapper/vg0-root /mnt
    mount /dev/mapper/vg0-usr /mnt/usr
    mount /dev/mapper/vg0-var /mnt/var
    mount /dev/mapper/vg1-home /mnt/home
    mount /dev/mapper/vg1-work /mnt/work

    mount /dev/sda1 /mnt/boot

    mount -o bind /dev /mnt/dev
    mount -o bind /dev/pts /mnt/dev/pts
    mount -o bind /dev/shm /mnt/dev/shm
    mount -o bind /sys /mnt/sys
    mount -o bind /proc /mnt/proc

    PATH=/bin:/sbin:/usr/bin:/usr/sbin \
    SHELL=/bin/bash \
    chroot /mnt

    Thanks for that, too. I actually created a small script with commands
    like these when I was installing Gentoo ~5 years ago, and I adapted
    that, saving the heavy labour of working out again that the flag in
    mount that I need is -o bind. :-)

    --
    Alan J. Wylie https://www.wylie.me.uk/

    Dance like no-one's watching. / Encrypt like everyone is.
    Security is inversely proportional to convenience

    --
    Alan Mackenzie (Nuremberg, Germany).

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