Discussion:
[linux-lvm] Recover LVM Volume Group when 2 physical disks removed
Traiano Welcome
2017-10-31 13:00:57 UTC
Permalink
Hi list


I'm trying to recover an LVM volume group that has had 2 of it's PVs
removed (these to PVs are beyond recovery).

The original volume group had 6 physical disks, only 4 remain now.
The missing PVs are the P0 and P1 in the set :-(


Is it possible to either:


a) Re-constitute the entire volume group without the missing PVs or

b) Recover the files on the PVs using some other method (I've tried
photorec, but that does not restore the file names)


Here is the current status of the VG (I've also appended the
original backup of the VG metadata at the end of this mail):



1) the VG is listed:



---

***@gamma2:/etc/lvm/backup# vgscan| egrep back


Found volume group "backupvg" using metadata type lvm2

---


2)


---

***@gamma2:/etc/lvm/backup# vgdisplay backupvg

--- Volume group ---

VG Name backupvg

System ID

Format lvm2

Metadata Areas 4

Metadata Sequence No 12

VG Access read/write

VG Status resizable

MAX LV 0

Cur LV 0

Open LV 0

Max PV 0

Cur PV 4

Act PV 4

VG Size 21.83 TiB

PE Size 4.00 MiB

Total PE 5723164

Alloc PE / Size 0 / 0

Free PE / Size 5723164 / 21.83 TiB

VG UUID OijmJo-thN5-wdHI-iHO6-WURZ-S4i0-GNPBOm

----


3) However it doesn't show up in /dev/mapper:


***@gamma2:/etc/lvm/backup# ls -l /dev/mapper/

total 0

crw------- 1 root root 10, 236 Oct 31 01:57 control

lrwxrwxrwx 1 root root 7 Oct 31 18:58 gamma2--vg-root -> ../dm-0

lrwxrwxrwx 1 root root 7 Oct 31 18:58 gamma2--vg-swap_1 -> ../dm-1

lrwxrwxrwx 1 root root 7 Oct 31 18:58 vg--data-lv--data -> ../dm-2


4) If I try to activate the VG it shows now Logical volumes present:


***@gamma2:/etc/lvm/backup# vgchange -a y backupvg

0 logical volume(s) in volume group "backupvg" now active



5) The (remaining) physical volumes are visible;


***@gamma2:/etc/lvm/backup# pvs

PV VG Fmt Attr PSize PFree

/dev/sda1 backupvg lvm2 a-- 5.46t 5.46t

/dev/sdb1 backupvg lvm2 a-- 5.46t 5.46t

/dev/sdc1 backupvg lvm2 a-- 5.46t 5.46t

/dev/sdd1 backupvg lvm2 a-- 5.46t 5.46t



***@gamma2:/etc/lvm/backup# lvs

LV VG Attr LSize Pool Origin Data% Meta%
Move Log Cpy%Sync Convert



6) Here is the last known good backup of the VG configuration:




# Generated by LVM2 version 2.02.133(2) (2015-10-30): Tue Oct 31 17:08:06 2017


contents = "Text Format Volume Group"

version = 1


description = "Created *before* executing 'vgs'"


creation_host = "gamma2" # Linux gamma2 4.4.0-87-generic
#110-Ubuntu SMP Tue Jul 18 12:55:35 UTC 2017 x86_64

creation_time = 1509440886 # Tue Oct 31 17:08:06 2017


backupvg {

id = "OijmJo-thN5-wdHI-iHO6-WURZ-S4i0-GNPBOm"

seqno = 5

format = "lvm2" # informational

status = ["RESIZEABLE", "READ", "WRITE"]

flags = []

extent_size = 8192 # 4 Megabytes

max_lv = 0

max_pv = 0

metadata_copies = 0


physical_volumes {


pv0 {

id = "MNTGzD-L2MT-2I7q-ZFdo-55I7-QniW-tXRS8U"

device = "unknown device" # Hint only


status = ["ALLOCATABLE"]

flags = ["MISSING"]

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}


pv1 {

id = "Ls67Tj-Ad0f-awoS-NoOH-u3f9-hNC7-9veW9W"

device = "unknown device" # Hint only


status = ["ALLOCATABLE"]

flags = ["MISSING"]

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}


pv2 {

id = "v1eYUS-BOdV-vBAe-CFw4-yFoj-zA1P-a9lld1"

device = "/dev/sda1" # Hint only


status = ["ALLOCATABLE"]

flags = []

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}


pv3 {

id = "BxRsPt-VRa1-xW9p-Uobn-COnn-l3A2-qYZA6u"

device = "/dev/sdb1" # Hint only


status = ["ALLOCATABLE"]

flags = []

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}


pv4 {

id = "9EGrfy-jgUX-cx78-Ocew-drV2-i8V6-iGbL5d"

device = "/dev/sdc1" # Hint only


status = ["ALLOCATABLE"]

flags = []

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}


pv5 {

id = "SGU0dD-Aqch-zV5E-6lt5-NcfV-AUvo-A3mIbv"

device = "/dev/sdd1" # Hint only


status = ["ALLOCATABLE"]

flags = []

dev_size = 11721041920 # 5.45804 Terabytes

pe_start = 2048

pe_count = 1430791 # 5.45803 Terabytes

}

}


logical_volumes {


backuplv {

id = "6V1b2C-PzGM-lgEy-YaSg-EFu5-iZ6u-wQVR9X"

status = ["READ", "WRITE", "VISIBLE"]

flags = []

creation_host = "gamma-compute2"

creation_time = 1507207639 # 2017-10-05 20:47:19 +0800

segment_count = 6


segment1 {

start_extent = 0

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv0", 0

]

}

segment2 {

start_extent = 1430791

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv1", 0

]

}

segment3 {

start_extent = 2861582

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv2", 0

]

}

segment4 {

start_extent = 4292373

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv3", 0

]

}

segment5 {

start_extent = 5723164

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv4", 0

]

}

segment6 {

start_extent = 7153955

extent_count = 1430791 # 5.45803 Terabytes


type = "striped"

stripe_count = 1 # linear


stripes = [

"pv5", 0

]

}

}

}

}

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