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Dear experts, I have a server with CentOS installed on it. The OS somehow stopped working and is said to have a kernel panic. Now i'm accessing that hard disk ...
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  1. #1
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    Exclamation Unable to mount / fsck a drive


    Dear experts,

    I have a server with CentOS installed on it. The OS somehow stopped working and is said to have a kernel panic.
    Now i'm accessing that hard disk from a secondary hard disk. The fdisk -l command gives the following:
    (Image attachment)
    Screenshot_2012-05-16-02-39-46-1.jpg

    When I try to mount it, I says: Wrong fs type, bad option, bad superblock on /dev/sdb2
    If you notice, sdb1 could be mounted without any issue.
    Screenshot_2012-05-16-02-47-21-1.jpg

    I wated to fix it using the fsck command but it won't work:
    I tried e2fsck -b 8193 but it does not work ..
    Screenshot_2012-05-16-02-48-44-1.jpg

    I seems like fsck will not be forced to use ext3 filesystem and it expects ext2. I read somewhere that it uses the values stored in fstab. The content of fstab file is shown here:
    Screenshot_2012-05-16-03-07-18-1.jpg

    I have very important data on that drive and I can't lose them in any way.
    I would appreciate if you please help me to find a solution for this drive.

  2. #2
    Super Moderator devils casper's Avatar
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    Hi and Welcome !

    You are executing wrong commands. /dev/sdb2 have Logical Volumes. You can run fsck or any other command like that on a LVM.
    Execute pvdisplay command and check if it lists Volume Group details.
    It is amazing what you can accomplish if you do not care who gets the credit.
    New Users: Read This First

  3. #3
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    But in the fdisk list, /dev/sdb2 is shown as a Linux LVM. Is that different from the LVM you are referring to ?

    This is the result of pvdisplay /dev/sdb2:
    Code:
     [root@server ~]# pvdisplay /dev/sdb2
      --- Physical volume ---
      PV Name               /dev/sdb2
      VG Name               VolGroup00
      PV Size               465.66 GB / not usable 3.56 MB
      Allocatable           yes (but full)
      PE Size (KByte)       32768
      Total PE              14901
      Free PE               0
      Allocated PE          14901
      PV UUID               MGxaT0-tmoo-xF1R-btxR-Afwc-LRXK-7LONUe
    Edit: No I know what I was doing wrong. An LVM partition can't be mounted same a normal partition. I tried to mount it using the LV Name but it gave some sector error. I rebooted the server and now the disk cannot be detected anymore. I forgot to mention that the disk can't be detected some times... I guess it has some hardware related problems.
    Last edited by FarshidT; 05-16-2012 at 05:14 AM.

  4. #4
    Linux User Krendoshazin's Avatar
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    This should be what you need to do to fsck an LVM partition.

    How to run fsck on a Linux file system | CentOS | Linux Tutorial
    Code:
    LVM Partitions
    
    In order to be able to run fsck on lvm partitions we need to find the pv’s, vg’s, lv’s and activate them.
    
    # lvm pvscan
    # lvm vgscan
    # lvm lvchange -ay /dev/VolGroup00/LogVol_home
    # lvm lvscan
    
    # fsck -yfv /dev/VolGroup00/LogVol_home

  5. #5
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    The disk does not accept commands anymore.
    Code:
    [root@ca ~]# fdisk -l
     
    Disk /dev/sda: 250.0 GB, 250000000000 bytes
    255 heads, 63 sectors/track, 30394 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
     
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1   *           1          13      104391   83  Linux
    /dev/sda2              14       30394   244035382+  8e  Linux LVM
    [root@ca ~]# lvdisplay /dev/sdb
      /dev/VolGroup01/LogVol00: read failed after 0 of 4096 at 495800221696: Input/output error
      /dev/VolGroup01/LogVol00: read failed after 0 of 4096 at 495800279040: Input/output error
      /dev/VolGroup01/LogVol00: read failed after 0 of 4096 at 0: Input/output error
      /dev/VolGroup01/LogVol00: read failed after 0 of 4096 at 4096: Input/output error
      /dev/VolGroup01/LogVol01: read failed after 0 of 4096 at 4194238464: Input/output error
      /dev/VolGroup01/LogVol01: read failed after 0 of 4096 at 4194295808: Input/output error
      /dev/VolGroup01/LogVol01: read failed after 0 of 4096 at 0: Input/output error
      /dev/VolGroup01/LogVol01: read failed after 0 of 4096 at 4096: Input/output error
      /dev/sdb: read failed after 0 of 4096 at 0: Input/output error
      /dev/sdb1: read failed after 0 of 2048 at 0: Input/output error
      /dev/sdb2: read failed after 0 of 2048 at 0: Input/output error
      /dev/sdb: read failed after 0 of 4096 at 500107771904: Input/output error
      /dev/sdb: read failed after 0 of 4096 at 500107853824: Input/output error
      /dev/sdb: read failed after 0 of 4096 at 4096: Input/output error
      /dev/sdb1: read failed after 0 of 1024 at 106823680: Input/output error
      /dev/sdb1: read failed after 0 of 1024 at 106885120: Input/output error
      /dev/sdb1: read failed after 0 of 1024 at 0: Input/output error
      /dev/sdb1: read failed after 0 of 1024 at 4096: Input/output error
      /dev/sdb2: read failed after 0 of 2048 at 499998195712: Input/output error
      /dev/sdb2: read failed after 0 of 2048 at 499998310400: Input/output error
      /dev/sdb2: read failed after 0 of 2048 at 4096: Input/output error
      Volume group "sdb" not found
      Skipping volume group sdb
    All lv and pv commands give similar errors. And this the result of fsck -yfv:
    Code:
     [root@ca ~]# fsck -yfv /dev/VolGroup01/LogVol00
    fsck 1.39 (29-May-2006)
    e2fsck 1.39 (29-May-2006)
    fsck.ext2: Attempt to read block from filesystem resulted in short read while trying to open /dev/VolGroup01/LogVol00
    Could this be a zero-length partition?
    [root@ca ~]# fsck.ext3 -yfv /dev/VolGroup01/LogVol00
    e2fsck 1.39 (29-May-2006)
    fsck.ext3: Attempt to read block from filesystem resulted in short read while trying to open /dev/VolGroup01/LogVol00
    Could this be a zero-length partition?
    Do you think this is a hardware issue?

    Thanks

  6. #6
    Super Moderator devils casper's Avatar
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    You have single Hard disk having two partition, sda1 and sda2. Execute commands on /dev/sda2 only.
    It is amazing what you can accomplish if you do not care who gets the credit.
    New Users: Read This First

  7. #7
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    Quote Originally Posted by devils casper View Post
    You have single Hard disk having two partition, sda1 and sda2. Execute commands on /dev/sda2 only.
    The disk with sda1 and sda2 is a disk that I added in order to access my other disk.
    The issue is with the disk containing sdb1 and sdb2. You can see it in the screenshot at post 1.

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