So my Fedora Linux machine crashed during an update, and now refuses to start properly. I'm using SystemRescueCD to try to recover the contents of the hard drive.
Following the steps in this post, I have done the following, shown together with the respective output for each command.
First I list the partitions:
root@sysresccd /root % fdisk -l
Disk /dev/loop0: 338.5 MiB, 354885632 bytes, 693136 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 /dev/sda: 477 GiB, 512110190592 bytes, 1000215216 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
Disklabel type: dos
Disk identifier: 0x283f70c2
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1026047 1024000 500M 83 Linux
/dev/sda2 1026048 1000214527 999188480 476.5G 8e Linux LVM
Disk /dev/mapper/fedora-swap: 7.6 GiB, 8187281408 bytes, 15990784 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 /dev/sdb: 7.5 GiB, 8076132352 bytes, 15773696 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
Disklabel type: dos
Disk identifier: 0x29ca9ce2
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 7641087 7639040 3.7G b W95 FAT32
The harddrive I want to access is in sda2, so I try to mount it.
root@sysresccd /root % mkdir /mnt/old
root@sysresccd /root % mount /dev/sda2 /mnt/old
mount: unknown filesystem type 'LVM2_member'
So it is unable to mount the hard drive because it does not recognise the filesystem.
With the lvm2 tools, I do a disk scan
root@sysresccd /root % lvmdiskscan
/dev/loop0 [ 338.45 MiB]
/dev/mapper/fedora-swap [ 7.62 GiB]
/dev/sda1 [ 500.00 MiB]
/dev/sda2 [ 476.45 GiB] LVM physical volume
/dev/sdb1 [ 3.64 GiB]
1 disk
3 partitions
0 LVM physical volume whole disks
1 LVM physical volume
With lvdisplay I get the logical volume (LV) name and the volume group (VG) name
root@sysresccd /root % lvdisplay
WARNING: Unrecognised segment type thin-pool
WARNING: Unrecognised segment type thin
--- Logical volume ---
LV Path /dev/fedora/pool00
LV Name pool00
VG Name fedora
LV UUID Ye2FvY-Sx80-znoh-aYdi-Q5wM-e0W3-UPaQtA
LV Write Access read/write
LV Creation host, time localhost, 2016-01-04 15:59:45 +0000
LV Status NOT available
LV Size 452.82 GiB
Current LE 115922
Segments 1
Allocation inherit
Read ahead sectors auto
--- Logical volume ---
LV Path /dev/fedora/root
LV Name root
VG Name fedora
LV UUID DLcLQA-VcRn-u7fQ-sWaL-v9cY-M5EW-F3ZFuN
LV Write Access read/write
LV Creation host, time localhost, 2016-01-04 15:59:46 +0000
LV Status NOT available
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
--- Logical volume ---
LV Path /dev/fedora/home
LV Name home
VG Name fedora
LV UUID aTrVab-urfB-u0xU-zoit-PK8H-l5Sf-2MfaXV
LV Write Access read/write
LV Creation host, time localhost, 2016-01-04 15:59:48 +0000
LV Status NOT available
LV Size 402.82 GiB
Current LE 103122
Segments 1
Allocation inherit
Read ahead sectors auto
--- Logical volume ---
LV Path /dev/fedora/swap
LV Name swap
VG Name fedora
LV UUID MuFrai-TMdG-uiap-y7fh-5lhU-dYlL-cjjBAZ
LV Write Access read/write
LV Creation host, time localhost, 2016-01-04 15:59:51 +0000
LV Status available
# open 0
LV Size 7.62 GiB
Current LE 1952
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
The vgdisplay command also gives similar information
root@sysresccd /root % vgdisplay
WARNING: Unrecognised segment type thin-pool
WARNING: Unrecognised segment type thin
--- Volume group ---
VG Name fedora
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 9
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 476.45 GiB
PE Size 4.00 MiB
Total PE 121971
Alloc PE / Size 117932 / 460.67 GiB
Free PE / Size 4039 / 15.78 GiB
VG UUID WduLzz-NwqH-DXYy-8fQy-ojos-SDi4-EmmHs5
Now I tried a new mount, using the LV name path:
root@sysresccd /root % mount /dev/fedora/home /mnt/old
mount: special device /dev/fedora/home does not exist
It still refuses to mount.
lvscan shows the status of the logical volume
root@sysresccd /root % lvscan
WARNING: Unrecognised segment type thin-pool
WARNING: Unrecognised segment type thin
inactive '/dev/fedora/pool00' [452.82 GiB] inherit
inactive '/dev/fedora/root' [50.00 GiB] inherit
inactive '/dev/fedora/home' [402.82 GiB] inherit
ACTIVE '/dev/fedora/swap' [7.62 GiB] inherit
As you can see, it is still inactive and not mounted. Also, there are two warnings about unrecognised segment types.
So even though I continue with the given instructions and add the device mapping module dm-mod to the kernel:
root@sysresccd /root % modprobe dm-mod
Then I change the attributes of the volume group:
root@sysresccd /root % vgchange -ay
WARNING: Unrecognised segment type thin-pool
WARNING: Unrecognised segment type thin
Refusing activation of LV pool00 containing an unrecognised segment.
Refusing activation of LV root containing an unrecognised segment.
Refusing activation of LV home containing an unrecognised segment.
1 logical volume(s) in volume group "fedora" now active
But the attributes do not change due to the unrecognised segments, and the logical volumes stay inactive.
root@sysresccd /root % lvscan
WARNING: Unrecognised segment type thin-pool
WARNING: Unrecognised segment type thin
inactive '/dev/fedora/pool00' [452.82 GiB] inherit
inactive '/dev/fedora/root' [50.00 GiB] inherit
inactive '/dev/fedora/home' [402.82 GiB] inherit
ACTIVE '/dev/fedora/swap' [7.62 GiB] inherit
I don't know what "thin" and "thin-pool" mean in this context, but it seems quite clear that they are blocking the access to the old partitions.
So if there is anyone who can spot the problem, please tell how to solve it.
