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I'm using Ubuntu and am getting an error that tells me the filesystem can not be identified when I try to mount a LVM ext3 disk. I'm passing "ext3" as the type and have been able to mount ext2 disks. How can I mount the image?

justforfun
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  • What is the full command line you are passing to do the mount? Have you attempted to leave "-t" off, or even try mounting it as ext2? – Alex Nov 02 '11 at 16:30
  • sudo mount -o loop,offset=106928640 /mnt I get this error: "mount: unknown filesystem type 'LVM2_member'" – justforfun Nov 02 '11 at 16:37
  • Is the file an image of an entire disk? Or of a single partition? If the image is of a disk, does the disk have partitions or is the entire device an LVM PV? – larsks Nov 02 '11 at 19:06
  • Entire disk. The first partition (boot) is recognized and mounted as /dev/sdb1 and the second partition is the LVM (sdb2) – justforfun Nov 02 '11 at 19:19
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    Try 'losetup /dev/loop0 ; kpartx -av /dev/loop0; vgdisplay; pvdisplay'? You'll need to have the partition recognised as a physical volume in your LVM volume group before you can mount the logical volume. – Andrew Nov 03 '11 at 01:07

1 Answers1

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LVM adds extra layers between the device and the filesystem; namely

  • devices become Physical Volumes (PVs)
  • PVs are part of a Volume Group (VG)
  • VGs contain Logical Volumes (LVs)
  • LVs contain filesystems

To access the filesystem on the image of an LVM disk, you need to

  1. Loop-mount the image with losetup /dev/loop0 <img.dd>
  2. Set up device maps with kpartx -av /dev/loop0
  3. Check for volume groups, physical volumes and logical volumes with vgdisplay, pvdisplay and lvdisplay
  4. Mount the relevant logical volume
Andrew
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    This might not work if the image is an old image of the PVs in the system - then the UUIDs, VG names and LV names inside it could collide... – glglgl Nov 14 '11 at 08:26