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Recovering data from a hard drive with LVM a partition

Hello all,

I have an external USB hard drive that I need to recover some data from, but I see from fdisk -l that the partition uses LVM:

Code:

[root@localhost ~]# fdisk -l /dev/sdd



Disk /dev/sdd: 160.0 GB, 160041885696 bytes

255 heads, 63 sectors/track, 19457 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes



  Device Boot      Start        End      Blocks  Id  System

/dev/sdd1  *          1      19457  156288321  8e  Linux LVM

[root@localhost ~]#

I've followed various lvm tutorials all of which describe setting up lvm from fresh on empty disks. Unfortunately non mention how to 'install' new a drive that was previously set up with lvm.

I have had a go anyway and may have now lost my data. Here's what I've ended up with (the partition in question is sdd1):

Code:

[root@localhost ~]# pvdisplay

  --- Physical volume ---

  PV Name              /dev/sdd1

  VG Name              vg02

  PV Size              149.05 GB / not usable 1.31 MB

  Allocatable          yes

  PE Size (KByte)      4096

  Total PE              38156

  Free PE              12

  Allocated PE          38144

  PV UUID              HmVjPK-gHmG-LJqF-jy1c-fQwK-M1KL-t0MlKs



  --- Physical volume ---

  PV Name              /dev/sda2

  VG Name              VolGroup00

  PV Size              7.90 GB / not usable 23.41 MB

  Allocatable          yes (but full)

  PE Size (KByte)      32768

  Total PE              252

  Free PE              0

  Allocated PE          252

  PV UUID              400PwS-P1j1-uQP0-2pNq-rqsL-DiNW-VYbM5j

Code:

[root@localhost ~]# vgdisplay

  --- Volume group ---

  VG Name              vg02

  System ID

  Format                lvm2

  Metadata Areas        1

  Metadata Sequence No  2

  VG Access            read/write

  VG Status            resizable

  MAX LV                0

  Cur LV                1

  Open LV              0

  Max PV                0

  Cur PV                1

  Act PV                1

  VG Size              149.05 GB

  PE Size              4.00 MB

  Total PE              38156

  Alloc PE / Size      38144 / 149.00 GB

  Free  PE / Size      12 / 48.00 MB

  VG UUID              TSEAlK-3HlT-utMW-0JEm-n45l-Hgmb-Vu4u1E



  --- Volume group ---

  VG Name              VolGroup00

  System ID

  Format                lvm2

  Metadata Areas        1

  Metadata Sequence No  3

  VG Access            read/write

  VG Status            resizable

  MAX LV                0

  Cur LV                2

  Open LV              2

  Max PV                0

  Cur PV                1

  Act PV                1

  VG Size              7.88 GB

  PE Size              32.00 MB

  Total PE              252

  Alloc PE / Size      252 / 7.88 GB

  Free  PE / Size      0 / 0

  VG UUID              BGOVZ1-5U0e-3ATo-XQLG-82l1-uuc8-hhaizP

Code:

[root@localhost ~]# lvdisplay

  --- Logical volume ---

  LV Name                /dev/vg02/lv02

  VG Name                vg02

  LV UUID                c2Ztsz-7yak-N5W0-aYs1-xXZd-lXQO-kC3VOs

  LV Write Access        read/write

  LV Status              available

  # open                0

  LV Size                149.00 GB

  Current LE            38144

  Segments              1

  Allocation            inherit

  Read ahead sectors    auto

  - currently set to    256

  Block device          253:2



  --- Logical volume ---

  LV Name                /dev/VolGroup00/LogVol00

  VG Name                VolGroup00

  LV UUID                gbFYmV-F8uI-81R5-mYSg-p8KW-HNgo-V0R4hg

  LV Write Access        read/write

  LV Status              available

  # open                1

  LV Size                7.38 GB

  Current LE            236

  Segments              1

  Allocation            inherit

  Read ahead sectors    auto

  - currently set to    256

  Block device          253:0



  --- Logical volume ---

  LV Name                /dev/VolGroup00/LogVol01

  VG Name                VolGroup00

  LV UUID                cCVgp7-5bXf-wfng-nyQO-e77D-aHgd-CBsI0B

  LV Write Access        read/write

  LV Status              available

  # open                1

  LV Size                512.00 MB

  Current LE            16

  Segments              1

  Allocation            inherit

  Read ahead sectors    auto

  - currently set to    256

  Block device          253:1

Code:

[root@localhost ~]# mkdir /media/sdd1/

[root@localhost ~]# mount /dev/vg02/lv02 /media/sdd1/

mount: you must specify the filesystem type

[root@localhost ~]# mount -t ext3 /dev/vg02/lv02 /media/sdd1/

mount: wrong fs type, bad option, bad superblock on /dev/vg02/lv02,

      missing codepage or other error

      In some cases useful info is found in syslog - try

      dmesg | tail  or so

I've tried mounting with other fstypes, but all give the same error.

Can anyone help me recover my data please?

Thanks,
Craig

Use "/sbin/vgmknodes" to create the /dev/dm-* nodes for the logical partition on the LVM volume. Then mount those nodes.

Hi jschiwal,

Thanks for your reply, unfortunately it didn't help on this occasion.

At first vgmknodes didn't seem to do anything, especially as nothing appears in /dev/dm-*, not even for the working LVM drives.

So I ran 'vgmknodes -v -v', part of the output is here:

Code:

      /dev/sdd1: lvm2 label detected

      Locking /var/lock/lvm/V_vg02 RB

      /dev/sdd1: lvm2 label detected

      /dev/sdd1: lvm2 label detected

      Removing /dev/vg02/lv02

      Linking /dev/vg02/lv02 -> /dev/mapper/vg02-lv02

      Unlocking /var/lock/lvm/V_vg02

So I guessed that my system uses /dev/mapper rather than /dev/dm-.

Next I tried 'mount /dev/mapper/vg02-lv02 /media/sdd1'', this failed as before, the same goes for using -t:

Code:

[root@localhost ~]# mount /dev/mapper/vg02-lv02 /media/sdd1/

mount: you must specify the filesystem type

[root@localhost ~]# mount -t ext3 /dev/mapper/vg02-lv02 /media/sdd1/

mount: wrong fs type, bad option, bad superblock on /dev/mapper/vg02-lv02,

      missing codepage or other error

      In some cases useful info is found in syslog - try

      dmesg | tail  or so

Thanks again,
Craig

You are mounting the correct device (either path should work). I think the problem is either with broken filesystem (try fsck) or another filesystem type (try using mount without the -t option).

A quick check on a partition is to run "sudo file -s /dev/<device>". It will tell you what filesystem is on it. Then you can run fsck.<filesystem> to check the filesystem for errors.

Sometimes there is a filesystem in /dev/mapper/ and another such as /dev/dm-0.

Also look at "ls -l /dev/disk/by-uuid/" and follow the links. Using UUID=<UUID #> in /etc/fstab is preferable for external drives.

Quote:

Originally Posted by r0b0 (Post 3831909)

You are mounting the correct device (either path should work). I think the problem is either with broken filesystem (try fsck) or another filesystem type (try using mount without the -t option).

Thanks robo, I tried mounting without the -t, but when that failed I tried using explicit types.

Quote:

Originally Posted by jschiwal (Post 3832049)

It never occurred to me to use 'file' in that way, that's really handy!

Unfortunately I think I have a stuffed file system :-( as 'file' doesn't come back with anything useful, and I think I've done everything correctly.

I'll have to read up on the UUID stuff as it didn't make sense on my system, the UUIDs in there weren't used by anything listed by pv/vg/lvdisplay. Thanks for the pointer though.

Thanks for your help but I'll give up on this now,
Craig

Be sure you use "file -s" on the logical volume. Using it on a Physical volume or volume group won't give you a filesystem.

If the logical volumes were used to create a raid array, then you may not have a filesystem on the logical volume.