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I have a server running Centos 6 in a data centre that suffered a kernal panic which then prevented the OS from booting (according to the support staff in the DC). The DC support staff also suggested they could not see the partitions. Unfortunately I have a file that I need to recover from the server. To help me the DC have attached a KVM and the SystemRescueCD ISO so I can now access the server via ssh / VCN. I've then run TestDisk.

I can see that the partitions with lsblk:

[root@sysresccd /]# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop0    7:0    0 632.2M  1 loop /run/archiso/sfs/airootfs
sda      8:0    0   1.8T  0 disk 
├─sda1   8:1    0   200M  0 part 
├─sda2   8:2    0     8G  0 part 
└─sda3   8:3    0   1.8T  0 part 
sr0     11:0    1   693M  0 rom  /run/archiso/bootmnt

But comparing that with my other similar server I can see that that has an LVM on sda3:

lsblk
NAME                        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                           8:0    0  1.8T  0 disk 
├─sda1                        8:1    0  200M  0 part /boot/efi
├─sda2                        8:2    0  500M  0 part /boot
└─sda3                        8:3    0  1.8T  0 part 
  ├─VolGroup-lv_root (dm-0) 253:0    0   50G  0 lvm  /
  ├─VolGroup-lv_swap (dm-1) 253:1    0  7.9G  0 lvm  [SWAP]
  └─VolGroup-lv_home (dm-2) 253:2    0  1.8T  0 lvm  /home
[root@gifted-hypatia /]#

Running TestDisk it seems to see the partitions :

Partition table type (auto): Intel
Disk /dev/sda - 2000 GB / 1863 GiB - ST2000DM001-1ER164
Partition table type: Intel

Analyse Disk /dev/sda - 2000 GB / 1863 GiB - CHS 243201 255 63
Geometry from i386 MBR: head=255 sector=63
Current partition structure:
 1 * Linux                    0  32 33    25 159  6     409600
 2 P Linux Swap              25 159  7  1069 244  7   16777216
 3 P Linux                 1069 244  8 243201  78 13 3889840128

But there are no files under P Linux other than lost+found.

I've been running around in circles for a day or so could someone help me understand what I would need to do to recover the partitions and the LVMs under sda3 so that I can try and recover a key file?  

Thanks Matt

1 Answer 1

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To get LVMs visible, you need to run

vgchange -ay

on the command prompt. This will make all volume groups active.

After this, the logical block devices are visible under /dev/mapper, and then you can mount the drives by running

mount /dev/mapper/<vgname> /mnt

Then you can access the logical volume files via /mnt directory.

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