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  1. #1

    Unhappy Question about filesystem of RAID6

    My question is whether a file system of Hardware RAID6 works the same as any file system. The problem is I need to recover data from a partially formatted file system implemented on RAID6.

  2. #2
    If your RAID is hardware based it has nothing to do with the file system being hosted. If you are using a software based RIAD then you will need to post more information on that. Also more information on how the data was lost would be helpful. In addition to the above more info about the installed OS would be helpful. If you are dealing with a failed drive in your RAID, mosst RAID controllers have the ability to recover the Array from the firmware.

    The most important thing to remember is make sure you do as little as possible with the file system until you are ready to attempt the recovery. By chance is this a LVM volume?

  3. #3
    The situation is that the LVM2 was made on a machine. OS specification is as follows:
    Distro = RHEL4
    Kernel = 2.6.9-5.ELsmp

    Now what has happened is that eight hardware RAID6 disk four (/dev/sda,/dev/sdb,/dev/sdc, /dev/sdd) on one side and four on the other side (/dev/sde,/dev/sdf,/dev/sdg, /dev/sdh) were combined to form an LVM2 partitions such that each side were made to be /dev/vg01/lvol0 and /dev/vg02/lvol0 by the commands:

    #lvcreate -name lvol0 --size 8T vg01
    #lvcreate -name lvol0 --size 8T vg02

    Now there was also an entry in /etc/fstab:

    /dev/vg01/lvol0 /var/export1 ext3 rw,noatime 0 0
    /dev/vg02/lvol0 /var/export2 ext3 rw,noatime 0 0

    where /var/export1 and /var/export2 are directories created with mkdir command.


    The device /dev/sda has accidentally been partially formatted i.e. I started formatting the file system of device /dev/sda and stopped half way through because I had picked the wrong device. It was approximately 15% formatted. Destro did not boot after that.

    Progress so Far:

    Destro was recovered by commenting the entries from /etc/fstab.

    By removing that disk and putting a blank one back will to it i.e. will it recover the data. Can LVM be recovered.


  4. $spacer_open
  5. #4
    Well... I can't make any promises about the data on the drive since you issued a format command. You may be able to recover the LVM since anytime you manipulate a LVM the config info should be automatically backed up to /etc/lvm/backup.
    Take a look in /etc/lvm/backup and make sure you find the most recent backup of the LVM config for each logical volume on your system. You use the vgcfgrestore command to restore the config.
    I can't stress enough that you need to read and then re-read the MAN page for this command before you attempt a restore. In fact you should at the very least Google the command and review some of the posts about it before you attempt to recover your system... please be very careful with this.
    Do you have a good back-up of your system? If not take some time and back-up anything that is of importance so that if things go bad and you are forced to rebuild the system from scratch you can at least restore some of the config files.

    Hope this helps.

  6. #5
    Thanks linlo68. Lets see what i will be able to do

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