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I had an old machine whose PSU crapped out. So I took whatever I could salvage (i.e. RAM, gfx card and the HDD which still had my arch installation) and merged it into a new machine. When I try to boot up the machine, it says cannot find root device with UUID-xxxxxx and it drops me into a recovery shell. After a bit of fiddling around I found out that the machine does boot into the fallback image and everything works perfectly. But when I reboot and try to boot into the normal image it says the same thing again.

I am a bit lost as to what is going on. Could someone explain to me what went wrong and how I can go about fixing this? Also, I am writing this from the new machine in the fallback image.

Cheers!

Edits :

/etc/fstab

# UUID=2932dc14-2339-4509-aa13-4131764a9bfe
/dev/sda5               /           ext4        rw,relatime,data=ordered    0 1

# UUID=ed251836-86aa-40ab-bd1f-b6f40937cb72
/dev/sda1               /boot       ext2        rw,relatime 0 2

# UUID=c2a8e803-2197-4130-99f3-6a43cfb43e73
/dev/sda7               /home       ext4        rw,relatime,data=ordered    0 2

#aravind@husker:/home/aravind/Work/  /home/aravind/Work   fuse.sshfs  noauto,x-systemd.automount,_netdev,users,IdentityFile=/home/aravind/.ssh/id_rsa,allow_other,reconnect,workaround=all   0   0

/var/log/dmesg.log

There is no dmesg.log or boot.log in /var/log/

Bootloader

Grub

Bootloader - config /boot/grub/grub.cfg

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
insmod part_gpt
insmod part_msdos
if [ -s $prefix/grubenv ]; then
  load_env
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

if [ x$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5  2932dc14-2339-4509-aa13-4131764a9bfe
else
  search --no-floppy --fs-uuid --set=root 2932dc14-2339-4509-aa13-4131764a9bfe
fi
    font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
fi
terminal_input console
terminal_output gfxterm
set timeout=5
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Arch Linux, with Linux core repo kernel' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-core repo kernel-true-2932dc14-2339-4509-aa13-4131764a9bfe' {
    load_video
    set gfxpayload=keep
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='hd0,msdos1'
    if [ x$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  ed251836-86aa-40ab-bd1f-b6f40937cb72
    else
      search --no-floppy --fs-uuid --set=root ed251836-86aa-40ab-bd1f-b6f40937cb72
    fi
    echo    'Loading Linux core repo kernel ...'
    linux   /vmlinuz-linux root=UUID=2932dc14-2339-4509-aa13-4131764a9bfe ro  quiet
    echo    'Loading initial ramdisk ...'
    initrd  /initramfs-linux.img
}
menuentry 'Arch Linux, with Linux core repo kernel (Fallback initramfs)' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-core repo kernel-fallback-2932dc14-2339-4509-aa13-4131764a9bfe' {
    load_video
    set gfxpayload=keep
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='hd0,msdos1'
    if [ x$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  ed251836-86aa-40ab-bd1f-b6f40937cb72
    else
      search --no-floppy --fs-uuid --set=root ed251836-86aa-40ab-bd1f-b6f40937cb72
    fi
    echo    'Loading Linux core repo kernel ...'
    linux   /vmlinuz-linux root=UUID=2932dc14-2339-4509-aa13-4131764a9bfe ro  quiet
    echo    'Loading initial ramdisk ...'
    initrd  /initramfs-linux-fallback.img
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  ${config_directory}/custom.cfg ]; then
  source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

### BEGIN /etc/grub.d/60_memtest86+ ###
### END /etc/grub.d/60_memtest86+ ###
  • 1
    Can you provide some information? What is content of a fstab file? Can you upload boot.log and dmesg located in /var/log? What kind of bootloader do you use? Can you upload bootloader's config file? – zuberuber Feb 16 '15 at 14:40
  • @zuberuber I just made an edit to the post with all the information you asked for – hRob Feb 16 '15 at 14:58
1

Try not using /dev/sdX to idendify your devices, instead use its UUID and you should always be safe.

Use the blkid command to identify your device's UUID and modify your fstab using UUID=YourDevicesUUID replacing /dev/sdX. You will also need to modify your /etc/grub/grub.cfg to set your root device as the UUID of the drive you want to boot from.

  • Hi @YoMismo, thanks for the suggestion. I have changed my fstab (after creating a backup) to use the UUIDs. How do I change grub.cfg though? Do I just change the lines set root='hd0,msdos1' to use UUIDs? Like set root=MyDeviceUUID? – hRob Feb 16 '15 at 16:31
  • No, use search instead search --no-floppy --fs-uuid --set=root YourDeviceUUID you will also need to modify your linux line adding the root. linux /vmlinuzblablabla root=UUID=YourDeviceUUID quiet .... – YoMismo Feb 16 '15 at 16:50
  • Thanks. I did the changes as you suggested, but it is still the same error. Boots into fallback image, but won't boot into the default image. Says its not able to find the UUID (I checked that the UUID for the device that fails matches the UUID for root) for the root device. – hRob Feb 16 '15 at 17:38
  • Weird. Have you added the UUID to all the entries in grub that refer to that drive?. Another solution would be to start with a live USB. Once the system has booted mount your drive. mount --bind /dev, /sys and /proc to those in the mounted directory where your new drive is. chroot to your mounted device and grub-install from there. But if your system is old (since it seemed to use /dev/sdX) it won't use the UUID :( – YoMismo Feb 17 '15 at 7:41
  • I think I found your problem. When setting root in your grub.cfg, the root does not refer to your / partition, it refers to /boot, you need to change that in your grub.cfg – YoMismo Feb 17 '15 at 8:04

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