Initial Situation

VG name = test
LV names = testlv1, testlv2

# mount /dev/test/testlv1 /DIR1
# mount /dev/test/testlv2 /DIR2
# ls -l /DIR1 /DIR2
/DIR1:
total 14680084
-rw-r--r-- 1 root root 15032385536 Sep 28 13:03 file
drwx------ 2 root root       16384 Sep 28 12:39 lost+found

/DIR2:
total 14680084
-rw-r--r-- 1 root root 15032385536 Sep 28 13:04 file2
drwx------ 2 root root       16384 Sep 28 12:39 lost+found

Problems: LVM Volume Group corrupted

Check Logical Volume status

# lvdisplay
  Couldn't find device with uuid memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
  --- Logical volume ---
  LV Path                /dev/test/testlv1
  LV Name                testlv1
  VG Name                test
  LV UUID                8jjBN7-m4wa-qxEq-rPL7-ET3E-yI9I-MxuVlo
  LV Write Access        read/write
  LV Creation host, time base, 2016-09-28 12:37:00 +0200
  LV Status              NOT available
  LV Size                15.00 GiB
  Current LE             3840
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto

  --- Logical volume ---
  LV Path                /dev/test/testlv2
  LV Name                testlv2
  VG Name                test
  LV UUID                4cXopI-qBvG-hOTZ-E9j6-ktoT-ZeyM-HO3911
  LV Write Access        read/write
  LV Creation host, time base, 2016-09-28 12:38:14 +0200
  LV Status              NOT available
  LV Size                14.98 GiB
  Current LE             3835
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto

The /dev/test/testlv1 and /dev/test/testlv2 are in status NOT available.

Check Volume Group status:

# vgdisplay
  Couldn't find device with uuid memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
  --- Volume group ---
  VG Name               test
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  6
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                2
  VG Size               29.99 GiB
  PE Size               4.00 MiB
  Total PE              7677
  Alloc PE / Size       7675 / 29.98 GiB
  Free  PE / Size       2 / 8.00 MiB
  VG UUID               cqLVSd-FhG1-bRGz-tj4u-SREG-z90p-pTbRft

The results tells us that something has happened to the integrity of the volume group’s disks: Could not find device with uuid memdmT-ge9I-Qbki-SV90-D4yU-Kz4Q-ow1pae

Check devices status:

# lvs -a -o +devices
  Couldn't find device with uuid memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
  LV      VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices
  root    base -wi-ao---- 34.38g                                                     /dev/sda5(0)
  swap_1  base -wi-ao----  1.50g                                                     /dev/sda5(8801)
  testlv1 test -wi-----p- 15.00g                                                     /dev/sdb1(0)
  testlv1 test -wi-----p- 15.00g                                                     unknown device(0)
  testlv2 test -wi-----p- 14.98g                                                     /dev/sdb3(0)
  testlv2 test -wi-----p- 14.98g                                                     unknown device(1281)

# pvscan
 Couldn't find device with uuid memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
 PV /dev/sdb1 VG test lvm2 [10.00 GiB / 0 free]
 PV unknown device VG test lvm2 [10.00 GiB / 8.00 MiB free]
 PV /dev/sdb3 VG test lvm2 [10.00 GiB / 0 free]
 PV /dev/sda5 VG base lvm2 [35.88 GiB / 0 free]
 Total: 4 [65.87 GiB] / in use: 4 [65.87 GiB] / in no VG: 0 [0 ]

A partition (10GB) used by VG test is missed (PV unknow device).

Recovery

In this case we have recreate another sdb2 partition (type LVM)

You may be able to find the UUID for the physical volume that was overwritten by looking in the /etc/lvm/archive directory.
Look in the file VolumeGroupName_xxxx.vg for the last known valid archived LVM metadata for that volume group.

Use the --uuid and --restorefile arguments of the pvcreate command to restore the physical volume.
The following example labels the /dev/sdb2 device as a physical volume with the UUID indicated above, memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
This command restores the physical volume label with the metadata information contained in test_00006-246083206.vg, the most recent good archived metatdata for volume group.
The restorefile argument instructs the pvcreate command to make the new physical volume compatible with the old one on the volume group, ensuring that the the new metadata will not be placed where the old physical volume contained data (which could happen, for example, if the original pvcreate command had used the command line arguments that control metadata placement, or it the physical volume was originally created using a different version of the software that used different defaults).
The pvcreate command overwrites only the LVM metadata areas and does not affect the existing data areas.

# pvcreate --uuid "memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae" --restorefile /etc/lvm/archive/test_00006-246083206.vg /dev/sdb2
  Couldn't find device with uuid memdmT-ge9I-Qbki-sV90-D4yU-Kz4Q-ow1pae.
  Physical volume "/dev/sdb2" successfully created

Check the situation now:

# lvs -a -o +devices
  LV      VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices
  root    base -wi-ao---- 34.38g                                                     /dev/sda5(0)
  swap_1  base -wi-ao----  1.50g                                                     /dev/sda5(8801)
  testlv1 test -wi------- 15.00g                                                     /dev/sdb1(0)
  testlv1 test -wi------- 15.00g                                                     /dev/sdb2(0)
  testlv2 test -wi------- 14.98g                                                     /dev/sdb3(0)
  testlv2 test -wi------- 14.98g                                                     /dev/sdb2(1281)

# pvscan
  WARNING: Volume Group test is not consistent
  PV /dev/sdb1   VG test   lvm2 [10.00 GiB / 0    free]
  PV /dev/sdb2   VG test   lvm2 [10.00 GiB / 8.00 MiB free]
  PV /dev/sdb3   VG test   lvm2 [10.00 GiB / 0    free]
  PV /dev/sda5   VG base   lvm2 [35.88 GiB / 0    free]
  Total: 4 [65.87 GiB] / in use: 4 [65.87 GiB] / in no VG: 0 [0   ]

The partition has been added to VG test and VG at the moment is not consistent.
testlv1 and testlv2 are now OK but not available infact there is not the “a” to the attribute (see the first result).

Activation LV:

# lvchange -ay /dev/test/testlv1
# lvchange -ay /dev/test/testlv2

Status:

# lvs -a -o +devices
  LV      VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices
  root    base -wi-ao---- 34.38g                                                     /dev/sda5(0)
  swap_1  base -wi-ao----  1.50g                                                     /dev/sda5(8801)
  testlv1 test -wi-a----- 15.00g                                                     /dev/sdb1(0)
  testlv1 test -wi-a----- 15.00g                                                     /dev/sdb2(0)
  testlv2 test -wi-a----- 14.98g                                                     /dev/sdb3(0)
  testlv2 test -wi-a----- 14.98g                                                     /dev/sdb2(1281)

LV activated. So, now is possible to check if there are files inside.

# mount /dev/test/testlv1 /DIR1
# mount /dev/test/testlv2 /DIR2
# ls -l /DIR1 /DIR2
/DIR1:
total 14680084
-rw-r--r-- 1 root root 15032385536 Sep 28 13:03 file
drwx------ 2 root root       16384 Sep 28 12:39 lost+found

/DIR2:
total 14680084
-rw-r--r-- 1 root root 15032385536 Sep 28 13:04 file2
drwx------ 2 root root       16384 Sep 28 12:39 lost+found

Drammatic case: all PV are lost

Example

# lvs -a -o +devices
  Couldn't find device with uuid 'FmGRh3-zhok-iVI8-7qTD-S5BI-MAEN-NYM5Sk'.
  Couldn't find all physical volumes for volume group VG.
  Couldn't find device with uuid 'FmGRh3-zhok-iVI8-7qTD-S5BI-MAEN-NYM5Sk'.
  Couldn't find all physical volumes for volume group VG.
  ...
# pvcreate --uuid "FmGRh3-zhok-iVI8-7qTD-S5BI-MAEN-NYM5Sk" --restorefile /etc/lvm/archive/VG_00050.vg /dev/sdh1
  Physical volume "/dev/sdh1" successfully created
# vgcfgrestore VG
  Restored volume group VG
# lvs -a -o +devices
  LV     VG   Attr   LSize   Origin Snap%  Move Log Copy%  Devices
  stripe VG   -wi--- 300.00G                               /dev/sdh1 (0),/dev/sda1(0)
  stripe VG   -wi--- 300.00G                               /dev/sdh1 (34728),/dev/sdb1(0)

The following commands activate the volumes and display the active volumes.

# lvchange -ay /dev/VG/stripe
# lvs -a -o +devices
  LV     VG   Attr   LSize   Origin Snap%  Move Log Copy%  Devices
  stripe VG   -wi-a- 300.00G                               /dev/sdh1 (0),/dev/sda1(0)
  stripe VG   -wi-a- 300.00G                               /dev/sdh1 (34728),/dev/sdb1(0)