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Thread: Grub error unknown filesystem

  1. #1
    Join Date
    Dec 2009
    Beans
    3
    Distro
    Ubuntu 9.10 Karmic Koala

    Grub error unknown filesystem

    My computer froze so I shut it down. When it rebooted i get
    Grub loading
    error unknown filesystem
    grub rescue

    ive been looking for solutions last night. I tried the one from
    http://help.ubuntu.com/community/Gru...lingfromLiveCD

    I can't get my hd with ubuntu 9.10 to mount.
    i type in sudo fdisk -l and this is what i get
    ubuntu@ubuntu:~$ sudo fdisk -l

    Code:
    Disk /dev/sda: 250.1 GB, 250059350016 bytes
    255 heads, 63 sectors/track, 30401 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Disk identifier: 0x4e608acb
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1   *           1       29275   235151406   83  Linux
    /dev/sda2           29276       30401     9044595    5  Extended
    /dev/sda5           29276       30401     9044563+  82  Linux swap / Solaris
    when i type in sudo blkid it give me this
    Code:
    ubuntu@ubuntu:~$ sudo blkid
    /dev/sda1: UUID="9075a94f-f190-4dba-a453-abb090e696db" TYPE="ext4" 
    /dev/sda5: UUID="6f722961-888c-4680-ad30-73c4e124cb99" TYPE="swap" 
    /dev/loop0: TYPE="squashfs"
    when i try and mount this is what it gives me
    Code:
    ubuntu@ubuntu:~$ sudo mount /dev/sda1/mnt
    mount: can't find /dev/sda1/mnt in /etc/fstab or /etc/mtab
    ubuntu@ubuntu:~$ sudo mount/dev/sda1/mnt
    sudo: mount/dev/sda1/mnt: command not found
    im out of ideas. i hope someone can help me out on this.

  2. #2
    Join Date
    Nov 2009
    Location
    Catalunya, Spain
    Beans
    14,377
    Distro
    Ubuntu 18.04 Bionic Beaver

    Re: Grub error unknown filesystem

    You are typing /dev/sda1/mnt together, at least here. It needs space in between, you are mounting /dev/sda1 to /mnt:
    sudo mount /dev/sda1 /mnt

    Also, if you experienced forced shutdown you might try fsck, a command to check the filesystem. It's even better to be run from LiveCD, LiveUSB. Root must NOT be mounted to do fsck. I haven't used the command myself, just saw it mentioned, you can google it for instructions to use.
    Darko.
    -----------------------------------------------------------------------
    Ubuntu 18.04 LTS 64bit

  3. #3
    Join Date
    Dec 2009
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    3
    Distro
    Ubuntu 9.10 Karmic Koala

    Re: Grub error unknown filesystem

    Ok i typed it the right way now and i get this
    Code:
    ubuntu@ubuntu:~$ sudo mount /dev/sda1 /mnt
    mount: wrong fs type, bad option, bad superblock on /dev/sda1,
           missing codepage or helper program, or other error
           In some cases useful info is found in syslog - try
           dmesg | tail  or so
    i tried using fsck but no luck. i think i might be typing the code wrong. sorry im kinda new to ubuntu.
    Code:
    ubuntu@ubuntu:~$ fsck /dev/sda1
    fsck from util-linux-ng 2.16
    e2fsck 1.41.9 (22-Aug-2009)
    fsck.ext2: Permission denied while trying to open /dev/sda1
    You must have r/w access to the filesystem or be root

  4. #4
    Join Date
    Nov 2009
    Location
    Catalunya, Spain
    Beans
    14,377
    Distro
    Ubuntu 18.04 Bionic Beaver

    Re: Grub error unknown filesystem

    If it says you have to be root, add 'sudo' in front of the command. But if /dev/sda1 is still mounted, unmount first.
    sudo umount /mnt
    sudo fsck /dev/sda1

    PS. Sorry, it didn't even mount, you said there was error. Just try the fsck command.
    Darko.
    -----------------------------------------------------------------------
    Ubuntu 18.04 LTS 64bit

  5. #5
    Join Date
    Dec 2009
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    3
    Distro
    Ubuntu 9.10 Karmic Koala

    Re: Grub error unknown filesystem

    omfg that worked!!! Thank you so much!!!! that was so simple and easier than replacing the grub. thank you once again!

  6. #6
    Join Date
    Nov 2009
    Location
    Catalunya, Spain
    Beans
    14,377
    Distro
    Ubuntu 18.04 Bionic Beaver

    Re: Grub error unknown filesystem

    No problem. We all learn here. Glad it got sorted.
    Darko.
    -----------------------------------------------------------------------
    Ubuntu 18.04 LTS 64bit

  7. #7
    Join Date
    Mar 2008
    Beans
    14

    Re: Grub error unknown filesystem

    This solution, if it actually is one, is not understandable by anyone not already well versed in command-line Linux. Tonight I tried to reinstall Kubuntu on a system that has had several different distros successfully installed on it before, including Ubuntu 9.10 and openSUSE 11.2, and I got this exact same error response described in the first post, when I first tried to boot Kubuntu after installing it.

    I have no idea what happened, nor why, and this thread has not helped me understand it at all. Would someone care to try again, in a more generalized fashion that doesn't read like some inside joke?

    There are some particulars to my setup that might be worth noting:
    - it is a dual-boot scenario, with Windows XP 32-bit in a second primary partition, and Kubuntu targeted to a new partition in empty space preceding it.
    - I use a boot MANAGER (not LOADER) called BootIt NG; because of that, I did NOT want grub/grub2 to be installed in the MBR, because BootIt NG manages the MBR interactively. As a consequence of that I instructed the installer to place grub in the Kubuntu root volume instead.

    During installation, the root volume was designated by /dev/sda2, and that is presumably where grub got installed. HOWEVER, in my subsequent attempts to understand what went wrong, it appears that /dev/sda2 has somehow magically become /dev/sda1! Whe I booted with the live CD, that is how it designated the root volume where it had been installed.

    Is that why I'm getting this error message from circumstances completely different than those in the original post? I have tried to reinstall/reactivate grub where it belongs, using both "grub rescue" and by booting back into the live CD, but I can't figure out how to correct it (in part because there's such a wealth of old/obsolete/unclear information available in forums and blogs). It was easy enough to verify with the live CD that all the Kubuntu files are there, in what the live CD at least identifies as /dev/sda1.

    So what's the problem here? Has the partition order somehow gotten confused, and so grub is trying to load itself from sda2 when in fact sda2 (now) doesn't contain Linux much less grub? The partition order might have been virtually altered by BootIt NG, because it has that ability to reorder the appearance of partitions in the MBR (and even exclude them), but to my knowledge I didn't do that in this case.

    How can I get grub (re)installed to the Kubuntu 9.10 partition, such that I can use BootIt to jumpstart grub and Linux from there?

  8. #8
    Join Date
    Apr 2008
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    3,317
    Distro
    Kubuntu 9.10 Karmic Koala

    Re: Grub error unknown filesystem

    VulcanTourist: We need more information. Please follow these instruction and post the RESULTS.txt.

  9. #9
    Join Date
    Mar 2008
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    14

    Re: Grub error unknown filesystem

    All I needed to know was how to reinstall grub to a specific location; I guess I wasn't specific enough, or perhaps too verbose. Why isn't there a GUI for that? Why isn't the ability to easily reinstall grub from a menu item a standard feature of every live CD? If the installer itself can automate that, why isn't that exposed as a separate feature of the live CD? It would have saved me something like an hour and a half.

    Lacking those specific instructions, I simply brute-forced it by reinstalling Kubuntu all over again, and once again using the Advanced button to force it to be installed in the root partition. That solved it, as I guessed it would.

    I also know how it happened: the ordering of the partitions changed between when I installed it and when I first tried to boot it. When I installed Kubuntu the first time, I was a bit lazy with BootIt and didn't pre-create the target partitions within BootIt and then create a boot menu item for the new install and "boot" to it - to "lock in" that particular partition scheme in the MBR - before booting from the CD. It's important to use BootIt to pre-create the partition(s) and then specify their use/ordering in a new boot menu item, because if the partitions don't yet exist and the OS installer creates them, then the partition ordering may change relative to what is defined in the boot menu for it.

    Instead I simply rebooted directly from Windows XP to the Kubuntu CD, which left the BootIt partition scheme for Windows XP in the MBR. After installing Kubuntu I created a new BootIt menu item for it, but in doing so I inadvertently altered the partition scheme and effectively guaranteed that grub wouldn't be able to find itself, because it wasn't looking on the partition where the grub stub loaded from, it was looking for itself on a particular ORDINAL partition... but that ordinal had now changed.

    It was effectively the same as what happens when partitions are reordered underneath NTLDR for Windows, and what's in boot.ini no longer jives with reality. I know well how to fix that scenario, but had no idea what the equivalent procedure is for Linux/grub even though I knew the issue was the same.

    Since I had already created a BootIt menu item for Kubuntu and defined the partition order for it at the time of the second install, and also tried to boot from it, that established the new partition order for that menu item and so when grub was configured by the installer the root partition ordinal was correct that time. That's the recommended procedure, and I didn't follow it this time. I now remember more clearly WHY it's the recommended procedure.

    By the way, I happened to find yet another forum post describing this exact same error, and do you know what advice the poor fool was given? He was eventually told to try swapping disks! Of course that worked for him, and everybody waltzed away believing there must have been something physically wrong with the original drive. No one ever corrected or questioned the bad advice. That incident demonstrates why forum discussions are a lousy means of disseminating wisdom.

  10. #10
    Join Date
    Apr 2008
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    Distro
    Kubuntu 9.10 Karmic Koala

    Re: Grub error unknown filesystem

    Since you installed Grub to the boot sector rather than to the MBR, you might run into the "rescue" prompt problem again. So just for future reference:

    To reinstall Grub if you cannot boot into Kubuntu, boot from the Kubuntu live CD, open a terminal (Applications ->System->Terminal) and type

    Code:
    sudo mount /dev/sda1  /mnt 
    sudo grub-install --recheck -f --root-directory=/mnt /dev/sda1
    (the first command mounts your Kubuntu partition so you can access it from the Live CD. The second command reinstalls grub.)

    This assume that Kubuntu is on "/dev/sda1". If not replace "/dev/sda1" by the correct partition for Kubuntu.



    It is also possible to install Grub so that it boots even if you change the Partition Table via BootIt NG:

    Open a terminal in Kubuntu (not in the LiveCD)

    Code:
    kdesudo kwrite /boot/grub/device.map
    Add the line:

    Code:
    (hd1) /dev/sda
    (This assumes that you have only one hard drive, if you have two, use "(hd2) /dev/sda" and so on.)
    Save the file.

    Then

    Code:
    sudo grub-install -f '(hd1,1)'
    (if you have two hard drives , use '(hd2,1)'. If Kubuntu is on /dev/sda2 use '(hd1,2)' ....)


    Could you do me a favor and run the boot info script and post the RESULTS.txt (see my last post)? You are only the second person I know who uses BootIT NG. The boot info script is able the read the BootIt NG partition table, but this feature has not been tested very much. So I would really like to see, how well it performs on our computer.
    Thanks
    Last edited by meierfra.; January 7th, 2010 at 09:44 PM.

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