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  1. #1

    Data loss on external harddisk? Input/Output errors


    My external harddisk used to work well, but suddenly

    -Dolphin file manager shows that almost all music and movie files have disappeard
    -Those files that can still be seen don't work when I open them (in VLC, I get an input/output error)
    -Also when opening other file types (pdf, etc) I get an input output error.
    -using the 'ls' command, ls says "ls: cannot access ***: input output error"

    However, the df command still shows that the ext drive is almost full

    What happened to my drive, and how can I fix this?

    I'm running a slightly outdated Fedora version (Fedora 19), the external hard drive is formatted with ext4 and encrypted.

    Thanks.
    Last edited by enoe; 11-07-2015 at 01:49 PM.

  2. #2
    Trusted Penguin Irithori's Avatar
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    call dmesg and look for io errors.
    Drives die, as any electronic device eventually.

    If a drive starts to show errors, then there is no fix.
    Recover from your latest backup if there is one.
    Otherwise try to copy the still readable data to another drive.
    You must always face the curtain with a bow.

  3. #3
    dmesg gives me these errors:

    [ 6855.803800] EXT4-fs error (device dm-7): __ext4_get_inode_loc:3940: inode #76283934: block 305135649: comm ls: unable to read itable block
    [ 6855.803811] EXT4-fs (dm-7): previous I/O error to superblock detected
    [ 6855.804057] Buffer I/O error on device dm-7, logical block 0
    [ 6855.804063] lost page write due to I/O error on dm-7
    [ 7879.003603] EXT4-fs warning (device dm-7): __ext4_read_dirblock:901: error reading directory block (ino 21364834, block 0)
    [ 9938.448295] Buffer I/O error on device dm-7, logical block 1
    [ 9938.450051] EXT4-fs (dm-7): unable to read superblock
    [10315.433431] Buffer I/O error on device dm-7, logical block 131072


    Also it seems the hard drive is mounted read only, though I'm not sure why.

    When trying to mount read/write I get:
    mount: /dev/mapper/** is write-protected, mounting read-only
    mount: /dev/mapper/**: can't read superblock

    Also running e2fsck on the partition I get:
    e2fsck: Attempt to read block from filesystem resulted in short read while trying to open /dev/mapper/**
    Could this be a zero-length partition?

    Is it possible to recover all the data with dd or with testdisk? I only have a partial backup of the drive unfortunately.

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  5. #4
    Trusted Penguin Irithori's Avatar
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    Your best chance is to use testdisk on the de-crypted device /dev/mapper/dm-7.
    There is no guarantee to get all data back.
    You must always face the curtain with a bow.

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