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Thread: EXT4 group descriptors corrupted

  1. #1
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    Default EXT4 group descriptors corrupted

    I have a second HD partitioned and formated to EXT4, the whole capacity. It was mounted to a directory in my home folder
    I'm getting an error that it cannot be mounted.

    Running "dmesg | tail" i get this: (rigt now the HD is connected to the computer using a USB adaptor)

    Code:
    laptop:~> dmesg | tail
    [  375.821495] sd 9:0:0:0: [sdb] Write Protect is off
    [  375.821505] sd 9:0:0:0: [sdb] Mode Sense: 00 38 00 00
    [  375.821512] sd 9:0:0:0: [sdb] Assuming drive cache: write through
    [  375.823508] sd 9:0:0:0: [sdb] Assuming drive cache: write through
    [  375.823519] sdb: detected capacity change from 0 to 320072933376
    [  375.832768]  sdb: sdb1
    [  375.834621] sd 9:0:0:0: [sdb] Assuming drive cache: write through
    [  375.834632] sd 9:0:0:0: [sdb] Attached SCSI disk
    [  376.360004] EXT4-fs (sdb1): ext4_check_descriptors: Block bitmap for group 1 not in group (block 1026)!
    [  376.360480] EXT4-fs (sdb1): group descriptors corrupted!

    What can i do to save the data ?
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

  2. #2

    Default Re: EXT4 group descriptors corrupted

    Have you tried to fsck the drive?

    If not something like this as root may fix things: fsck.ext4 -y -f /dev/sdb1

    It may take quite a while to run so just let it do it's thing

    Incidentally if you have the drive as a persistent mount wouldn't it be better to use the drive as internal rather than usb?

    Personally I wouldn't persistently mount a usb drive as they just aren't reliable enough and if anything 'breaks' the usb connection while it's being written like the lead getting slightly dislodged for example, you can end up with filesystem corruption, and it very much looks like that's what might have happened in your case

  3. #3
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    Default Re: EXT4 group descriptors corrupted

    Quote Originally Posted by Ecky View Post
    Incidentally if you have the drive as a persistent mount wouldn't it be better to use the drive as internal rather than usb?

    Personally I wouldn't persistently mount a usb drive as they just aren't reliable enough and if anything 'breaks' the usb connection while it's being written like the lead getting slightly dislodged for example, you can end up with filesystem corruption, and it very much looks like that's what might have happened in your case
    That is the situation on my system, but because i had a total system meltdown, i'm trying to access the data on the HD from a laptop, hence the USB adaptor.

    I will check the command you suggested.
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

  4. #4

    Default Re: EXT4 group descriptors corrupted

    If fsck finds and fixes errors, which it's usually pretty good at doing unless a drive is physically failing you've a good chance of getting at your data after it's finished running

  5. #5
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    Default Re: EXT4 group descriptors corrupted

    OK, I ran the fsck command. it finished and apparently it was fixed. But when i mount the drive "mount /dev/sdb1 ~/Disk2" all i see is an empty drive.

    If i run 'df -h /dev/sdb1' i get:

    > df -h /dev/sdb1
    Filesystem Size Used Avail Use% Mounted on
    /dev/sdb1 294G 185G 94G 67% /home/ronen/Disk2


    Which means there are files on that drive (or at least the file system thinks there are files).
    What can i do to retrieve them ?

    thank you
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

  6. #6
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    Default Re: EXT4 group descriptors corrupted

    Remember that the filesystem objects still retain their ownership info even though the filesystem is mounted under your home. So you may need to access them as root.

  7. #7
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    Default Re: EXT4 group descriptors corrupted

    I am the owner of those files. before the crash, the drive was mounted to the directory under my home, using the same user name
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

  8. #8
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    Default Re: EXT4 group descriptors corrupted

    Quote Originally Posted by Argoson View Post
    I am the owner of those files. before the crash, the drive was mounted to the directory under my home, using the same user name
    I think i know what happened. the recovered files are in the lost+found folder. if i open the folder as root i can see them.

    now... i need to know how to recover them....
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

  9. #9
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    Default Re: EXT4 group descriptors corrupted

    Unfortunately you just have to try to guess the original name of the file from the contents. The "file" command can help you guess what it might be.

  10. #10
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    Default Re: EXT4 group descriptors corrupted

    Quote Originally Posted by ken_yap View Post
    Unfortunately you just have to try to guess the original name of the file from the contents. The "file" command can help you guess what it might be.
    What do you think about these instructions ?
    WE ARE LINUX... RESISTANCE IS FUTILE !!
    openSUSE 13.1, KDE
    2 daughters, 1 Dog, lots of passion for Linux

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