Lubuntu 14.04LTS fails to boot after updates - GRUB issue

Question

I have been running Lubuntu 14.04 LTS for more than a year without (significant) issues. I postponed rebooting after a few updates recently (probably about 2-3 weeks) and when I finally had the time to reboot, I was greeted by a busybox ash prompt with messages indicating it had tried to mount my RAID partitions on /root which it could not (/dev/md127 is my root partition managed via mdadm). The message said something like Could not find init at /sbin/init. This was when trying to boot into kernel 3.13.0-88

Luckily I had a working RAID config saved as a "custom" GRUB entry (with a kernel version of 3.13.0-57) and I could boot into this, and managed to change the grub.cfg definition for that entry to get me to kernel 3.13.0-88. At least that got me back into my system, but as soon as an update-grub command gets run the config gets overwritten.

How can I fix my Grub2 setup in such a way that it does recognize my RAID array(s), and so that the setup becomes permanent even when update-grub gets run? For reference, here is the grub.cfg entry for the failing boot:

menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd' {
    recordfail
    load_video
    gfxmode $linux_gfx_mode
    insmod gzio
    insmod part_msdos
    insmod part_msdos
    insmod diskfilter
    insmod mdraid1x
    insmod ext2
    set root='mduuid/dfe0e47f47757b9c579476231666f004'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint='mduuid/dfe0e47f47757b9c579476231666f004'  ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd
    else
      search --no-floppy --fs-uuid --set=root ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd
    fi
    linux   /boot/vmlinuz-3.13.0-88-generic root=UUID=ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd ro  quiet splash nomdmonddf nomdmonisw bootdegraded=true $vt_handoff
    initrd  /boot/initrd.img-3.13.0-88-generic

And here is the grub.cfg entry for the working RAID custom entry:

menuentry 'Ubuntu (RAID)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd' {
        recordfail
        load_video
        gfxmode $linux_gfx_mode
        insmod gzio
        insmod part_msdos
        insmod ext2
        insmod mdraid1x
        set root='hd0,msdos1'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd 
        else
          search --no-floppy --fs-uuid --set=root ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd 
        fi
        linux   /boot/vmlinuz-3.13.0-57-generic root=UUID=ac8ee99a-72a5-4ab9-8059-bb4841d3a1fd ro  quiet splash nomdmonddf nomdmonisw nomdmonddf nomdmonisw bootdegraded=true $vt_handoff 
        initrd  /boot/initrd.img-3.13.0-57-generic

Any suggestions would be most appreciated.

Answer 1

Well - looks like all I needed to do was rerun update-grub. The grub.cfg entry I posted in my question was already fixed by grub2 itself - something must have gone bad during one of the updates. Originally, the broken grub.cfg entry showed root=/dev/md127 instead of the root=UUID=... line. The above grub.cfg boots properly. Issue solved.