LinuxQuestions.org - [SOLVED] question about LVM with a DD image from full disk?

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question about LVM with a DD image from full disk?

I made a full disk backup using dd earlier today on an Ubuntu LTS 14.04 system running a LVM partition.

I am able to mount the .img file and see the /boot but im unable to get to the LVM, then when I attempt the following:

Code:

[root@jackknife ~]# fdisk -lu /exports/backup/BOAT/BOAT.img



Disk /exports/backup/BOAT/BOAT.img: 120.0 GB, 120034123776 bytes, 234441648 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x000a2421



                        Device Boot      Start        End      Blocks  Id  System

/exports/backup/BOAT/BOAT.img1  *        2048      499711      248832  83  Linux

/exports/backup/BOAT/BOAT.img2          501758  234440703  116969473    5  Extended

/exports/backup/BOAT/BOAT.img5          501760  234440703  116969472  8e  Linux LVM

[root@jackknife ~]# kpartx -av /exports/backup/BOAT/BOAT.img

[root@jackknife ~]# umount /mnt/old/

[root@jackknife ~]# mount -o loop,offset=256901120 /exports/backup/BOAT/BOAT.img /mnt/old/

mount: unknown filesystem type 'LVM2_member'

Im sure there is just something simple I'm missing.

Code:

[root@jackknife ~]# mount -o loop,offset=1048576 /exports/backup/BOAT/BOAT.img /mnt/old/

[root@jackknife ~]# d /mnt/old/

total 62298

drwxr-xr-x. 4 root root    1024 May 18 18:43 ./

drwxr-xr-x. 5 root root      37 Apr 19 16:15 ../

-rw-r--r--. 1 root root  1207386 Jan 15 13:22 abi-3.16.0-30-generic

-rw-r--r--. 1 root root  1206938 May  6 12:22 abi-3.16.0-37-generic

-rw-r--r--. 1 root root  171768 Jan 15 13:22 config-3.16.0-30-generic

-rw-r--r--. 1 root root  171816 May  6 12:22 config-3.16.0-37-generic

drwxr-xr-x. 5 root root    1024 May 18 18:43 grub/

-rw-r--r--. 1 root root 20246540 May 18 15:46 initrd.img-3.16.0-30-generic

-rw-r--r--. 1 root root 20249911 May 18 18:43 initrd.img-3.16.0-37-generic

drwx------. 2 root root    12288 May 18 15:15 lost+found/

-rw-r--r--. 1 root root  176500 Mar 12  2014 memtest86+.bin

-rw-r--r--. 1 root root  178176 Mar 12  2014 memtest86+.elf

-rw-r--r--. 1 root root  178680 Mar 12  2014 memtest86+_multiboot.bin

-rw-------. 1 root root  3511040 Jan 15 13:22 System.map-3.16.0-30-generic

-rw-------. 1 root root  3512899 May  6 12:22 System.map-3.16.0-37-generic

-rw-r--r--. 1 root root  6345120 May 18 15:17 vmlinuz-3.16.0-30-generic

-rw-------. 1 root root  6352688 May  6 12:22 vmlinuz-3.16.0-37-generic

so i can mount it, just can not gain access to the LVM partition. this is were my data resides. help is greatly appreciated in advance. Thank you.

You can only mount filesystems, not (block) devices. Attempting to mount the "LVM Member" is akin to trying to mount /dev/sda (when /dev/sda has partitions).
I imagine vgscan should find your vg(s) - then you'd have to activate it/them with vgchange then mount them. Remember to reverse it all when finished.

Another reason to add to my long list of not advocating image backups.

Since your image will contain an LVM structure identical to the one you copied it from, you cannot have both the original and the copy connected to the system at the same time. They have the same VG and LV names, and the same PV, VG, and LV UUIDs. When accessing an LV, the system will randomly select one or the other. With the system already up and running, connecting the other disk won't cause confusion; you just won't be able to access it. Should you be so unfortunate as to boot with both copies connected, you would need to run "pvs" to see which physical volumes were actually in use.

after mounting as the successful way in the first post, neither vgscan or pvscan detect the LVM on the .img mounted system.

no the LCM structure is not identical as it is not from the live system, it is from an external HDD, has nothing to do with it.

Instead of using offset with loop device you can with recent util-inux create multiple block devices for each partition and then mount fs or use for other purposes.

See this link.

As stated you can not mount a volume group image the same way as you mount a regular partition image. Check out the links before. Your setting up the loop device to the LVM partition then mounting the volume group.

http://www.utilities-online.info/art.../#.VWHedGGQlpU
http://forensicswiki.org/wiki/Linux_..._from_an_image

Quote:

Originally Posted by lleb (Post 5366743)

no the LCM structure is not identical as it is not from the live system, it is from an external HDD, has nothing to do with it.

OK, good.

Your original post showed no output from the "kpartx -av /exports/backup/BOAT/BOAT.img" command. With that "-v" option, I would expect to see output like

Code:

add map loop0p1 (253:3): 0 6848224 linear /dev/loop0 32

add map loop0p2 (253:4): 0 1048832 linear /dev/loop0 6848256

and those "loop?p?" block devices are what pvscan should be examining and finding the LVM structure. Did no loop devices show up in /dev/mapper after that kpartx command? That sounds like the key to the problem.

Quote:

Originally Posted by rknichols (Post 5366769)

OK, good.

Your original post showed no output from the "kpartx -av /exports/backup/BOAT/BOAT.img" command. With that "-v" option, I would expect to see output like

Code:

add map loop0p1 (253:3): 0 6848224 linear /dev/loop0 32

add map loop0p2 (253:4): 0 1048832 linear /dev/loop0 6848256

running the kpartx -av did the trick. that allowed pvscan to detect the LVM i was missing earlier. now i should be able to access, ill report back with progress:

Code:

[root@jackknife ~]# kpartx -av /exports/backup/BOAT/BOAT.img

add map loop1p1 (253:3): 0 497664 linear /dev/loop1 2048

add map loop1p2 (253:4): 0 2 linear /dev/loop1 501758

add map loop1p5 (253:5): 0 233938944 linear /dev/loop1 501760

[root@jackknife ~]# df -Th

Filesystem    Type      Size  Used Avail Use% Mounted on

/dev/md127    xfs        20G  14G  6.0G  70% /

devtmpfs      devtmpfs  7.7G    0  7.7G  0% /dev

tmpfs          tmpfs    7.8G  4.0K  7.8G  1% /dev/shm

tmpfs          tmpfs    7.8G  17M  7.7G  1% /run

tmpfs          tmpfs    7.8G    0  7.8G  0% /sys/fs/cgroup

/dev/sda2      xfs      506M  262M  245M  52% /boot

/dev/md126    xfs        30G  21G  9.0G  70% /home

/dev/md125    xfs        11T  7.4T  3.6T  68% /exports

/dev/loop0    udf      4.4G  4.4G    0 100% /mnt/ISO

[root@jackknife ~]# pvscan

  PV /dev/mapper/loop1p5  VG ubuntu-vg          lvm2 [111.55 GiB / 0    free]

  PV /dev/sda5            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdb3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdc3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdd3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sde3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdf3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  Total: 7 [113.49 GiB] / in use: 7 [113.49 GiB] / in no VG: 0 [0  ]

so im doing something horridly wrong:

Code:

[root@jackknife ~]# mount /dev/mapper/loop1p5 /mnt/home/

mount: unknown filesystem type 'LVM2_member'

[root@jackknife ~]# kpartx -av /exports/backup/BOAT/BOAT.img

add map loop1p1 (253:3): 0 497664 linear /dev/loop1 2048

add map loop1p2 (253:4): 0 2 linear /dev/loop1 501758

add map loop1p5 (253:5): 0 233938944 linear /dev/loop1 501760

[root@jackknife ~]# pvscan

  PV /dev/mapper/loop1p5  VG ubuntu-vg          lvm2 [111.55 GiB / 0    free]

  PV /dev/sda5            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdb3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdc3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdd3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sde3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  PV /dev/sdf3            VG centos_jackknife  lvm2 [332.00 MiB / 0    free]

  Total: 7 [113.49 GiB] / in use: 7 [113.49 GiB] / in no VG: 0 [0  ]

[root@jackknife ~]# vgscan

  Reading all physical volumes.  This may take a while...

  Found volume group "ubuntu-vg" using metadata type lvm2

  Found volume group "centos_jackknife" using metadata type lvm2

[root@jackknife ~]# mount -t ext3 /dev/mapper/loop1p5 /mnt/home/

mount: /dev/mapper/loop1p5 is already mounted or /mnt/home busy

[root@jackknife ~]# d /mnt/home/

total 0

drwxr-xr-x. 2 root root  6 Dec 17 07:55 ./

drwxr-xr-x. 5 root root 37 Apr 19 16:15 ../

[root@jackknife ~]# cd /dev/mapper/loop1p5

-bash: cd: /dev/mapper/loop1p5: Not a directory

[root@jackknife ~]# d /dev/mapper/loop1p5

lrwxrwxrwx. 1 root root 7 May 24 12:14 /dev/mapper/loop1p5 -> ../dm-5

[root@jackknife ~]# d /dm-t

/bin/ls: cannot access /dm-t: No such file or directory

how can i access the LVM partition from the .img file if i do not mount the .img?

FYI, my system is CentOS v7, yes it an Ubuntu system I'm attempting to gain access to. I know the Ubuntu does some strange stuff with their LVM's is that the problem?

nm, im a total idiot. i was mounting the wrong LVM on the .img:

Code:

[root@jackknife ~]# lvmdiskscan /mnt/old/

  /dev/loop0                [      4.36 GiB]

  /dev/centos_jackknife/swap [      1.95 GiB]

  /dev/loop1                [    111.79 GiB]

  /dev/ubuntu-vg/root        [    103.66 GiB]

  /dev/sda2                  [    512.00 MiB]

  /dev/ubuntu-vg/swap_1      [      7.89 GiB]

  /dev/mapper/loop1p1        [    243.00 MiB]

  /dev/sda5                  [    333.00 MiB] LVM physical volume

  /dev/mapper/loop1p5        [    111.55 GiB] LVM physical volume

  /dev/sdb3                  [    333.00 MiB] LVM physical volume

  /dev/sdc3                  [    333.00 MiB] LVM physical volume

  /dev/sdd3                  [    333.00 MiB] LVM physical volume

  /dev/sde3                  [    333.00 MiB] LVM physical volume

  /dev/sdf3                  [    333.00 MiB] LVM physical volume

  /dev/sdh                  [      1.91 GiB]

  /dev/md125                [      10.86 TiB]

  /dev/md126                [      29.34 GiB]

  /dev/md127                [      19.57 GiB]

  3 disks

  8 partitions

  0 LVM physical volume whole disks

  7 LVM physical volumes

[root@jackknife ~]# lvdisplay /mnt/old/

  "/mnt/old/": Invalid path for Logical Volume.

[root@jackknife ~]# lvdisplay ubuntu-vg

  --- Logical volume ---

  LV Path                /dev/ubuntu-vg/root

  LV Name                root

  VG Name                ubuntu-vg

  LV UUID                0vyHeH-W7Xs-QadH-evLz-cp1s-nsmO-G2AUS5

  LV Write Access        read/write

  LV Creation host, time ubuntu, 2015-05-18 15:15:07 -0400

  LV Status              available

  # open                0

  LV Size                103.66 GiB

  Current LE            26536

  Segments              1

  Allocation            inherit

  Read ahead sectors    auto

  - currently set to    256

  Block device          253:1



  --- Logical volume ---

  LV Path                /dev/ubuntu-vg/swap_1

  LV Name                swap_1

  VG Name                ubuntu-vg

  LV UUID                9w32hF-Rd4v-02W3-wGn1-9P1W-L0W1-cUzJzO

  LV Write Access        read/write

  LV Creation host, time ubuntu, 2015-05-18 15:15:07 -0400

  LV Status              available

  # open                0

  LV Size                7.89 GiB

  Current LE            2020

  Segments              1

  Allocation            inherit

  Read ahead sectors    auto

  - currently set to    256

  Block device          253:2



[root@jackknife ~]# lvscan

  ACTIVE            '/dev/ubuntu-vg/root' [103.66 GiB] inherit

  ACTIVE            '/dev/ubuntu-vg/swap_1' [7.89 GiB] inherit

  ACTIVE            '/dev/centos_jackknife/swap' [1.95 GiB] inherit

[root@jackknife ~]# mount /dev/ubuntu-vg/root /mnt/home/

Success... marking post as such. Thanks for pointing me in the right direction.