How to rescue data from an LVM disk

Recently my laptop broke down, but the hard drive was still functioning. I wanted to rescue as mucht data from it as possible as simple as possible. I had forgotten that the Fedora installation was using LVM so when I went to get the data I had to learn a little about LVM.

From hard disk to mountable "partition" LVM is divided in physical volumes, volume groups and logical volumes. So I had to find the physical volume, activate the volume group and mount the logical volume.

I removed the harddisk from the laptop and mounted in an USB to 2.5" hard disk enclosure. I attached the USB connector to the Linux machine I used to rescue the data. When I connected the USB enclosure to the computer /var/log/messages showed me the name of the disk (in this case /dev/sdb). Using pvscan I found that Linux recognized there was a SCSI disk connected to the computer that contained an LVM volume. This matched the information from /var/log/messages, so I knew I was on the right track.

Oct 16 16:55:05 lusitania kernel: usb 1-1: new full speed USB device using uhci_hcd and address 3
Oct 16 16:55:05 lusitania crond(pam_unix)[4577]: session closed for user root
Oct 16 16:55:11 lusitania kernel: Initializing USB Mass Storage driver...
Oct 16 16:55:11 lusitania kernel: scsi2 : SCSI emulation for USB Mass Storage devices
Oct 16 16:55:11 lusitania kernel: usbcore: registered new driver usb-storage
Oct 16 16:55:11 lusitania kernel: USB Mass Storage support registered.
Oct 16 16:55:16 lusitania kernel:   Vendor: FUJITSU   Model: MHT2060AH         Rev: 006C
Oct 16 16:55:16 lusitania kernel:   Type:   Direct-Access                      ANSI SCSI revision: 00
Oct 16 16:55:16 lusitania kernel: SCSI device sdb: 117210240 512-byte hdwr sectors (60012 MB)
Oct 16 16:55:16 lusitania kernel: sdb: assuming drive cache: write through
Oct 16 16:55:16 lusitania kernel: SCSI device sdb: 117210240 512-byte hdwr sectors (60012 MB)
Oct 16 16:55:16 lusitania kernel: sdb: assuming drive cache: write through
Oct 16 16:55:16 lusitania kernel:  sdb: sdb1 sdb2 sdb3 sdb4 
Oct 16 16:55:16 lusitania kernel: Attached scsi disk sdb at scsi2, channel 0, id 0, lun 0
Oct 16 16:55:20 lusitania scsi.agent[4681]: disk at /devices/pci0000:00/0000:00:02.2/usb1/1-1/1-1:1.0/host2/target2:0:0/2:0:0:0

[root@lusitania andreas]# pvscan
  PV /dev/sdb5   VG VolGroup00   lvm2 [31.31 GB / 32.00 MB free]
  PV /dev/hda3   VG System       lvm2 [3.50 GB / 32.00 MB free]
  PV /dev/sda1   VG Data         lvm2 [189.91 GB / 32.00 MB free]
  Total: 3 [224.72 GB] / in use: 3 [224.72 GB] / in no VG: 0 [0   ]
[root@lusitania andreas]# 

So there's something called VolGroup00 that should contain the data I'm after. Now I have to activate it so I can get to the data:

[root@lusitania andreas]# vgchange -ay VolGroup00

vgdisplay shows quite a lot of information about the volume groups it finds. Here's the most useful part of the information it generated:

  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol00
  VG Name                VolGroup00
  LV UUID                8W0wHB-f076-UaNj-93yx-p8O0-fbjH-YUHdu9
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                29.78 GB
  Current LE             953
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:4
  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol01
  VG Name                VolGroup00
  LV UUID                q9u8Pg-eRFw-BAZO-GzEw-V8uG-qQTL-hLpP2A
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                1.50 GB
  Current LE             48
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:5

One of the two logical volumes inside is the swap partition and the other shoulde then be the big / partition of my laptop and contain the data I'm after.

Mounting /dev/VolGroup00/LogVol00 as if it was a normal ext3 partition gave me the access to the data:

```bash
[root@lusitania andreas]# mount /dev/VolGroup00/LogVol00 usbdisk