LVM Volume Group Shows "unknown device"

This document (3803380) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 10
SUSE Linux Enterprise Server 9
Logical Volume Management Version 2 (LVM)
 

Situation

When an LVM volume group is activated, it displays an "unknown device" error. The logical volumes will not activate.

# pvscan
Couldn't find device with uuid '56ogEk-OzLS-cKBc-z9vJ-kP65-DUBI-hwZPSu'.
Couldn't find device with uuid '56ogEk-OzLS-cKBc-z9vJ-kP65-DUBI-hwZPSu'.
PV /dev/sdb VG ops lvm2 [200.00 MB / 0 free]
PV unknown device VG ops lvm2 [200.00 MB / 0 free]
PV /dev/sdd VG sales ops [200.00 MB / 150.00 MB free]
Total: 4 [600.00 MB] / in use: 4 [600.00 MB] / in no VG: 0 [0 ]

When When a physical disk is removed from a volume group containing multiple disks, it will also result in a paritial mode volume group. In the example below, the lrg volume group is missing one of its disks, resulting in partial mode.

# /sbin/vgs
  Couldn't find device with uuid ntc7O9-wevl-ZtXz-xESe-wwUB-G8WZ-6RtjxB.
  VG   #PV #LV #SN Attr   VSize   VFree 
  asm    1   2   0 wz--n- 300.00m  60.00m
  ceo    1   1   0 wz--n- 252.00m  12.00m
  lrg    4   1   0 wz-pn-   1.19g 716.00m
  sys    1   3   0 wz--n-   3.50g  12.00m

 

Resolution

Generally this error means the physical device is missing or the LVM meta data on the device is corrupted or missing. The general procedure to recover the volume is:

1. Replace the failed or missing disk
2. Restore the missing disk's UUID
3. Restore the LVM meta data
4. Repair the file system on the LVM device

Scenario 1:
If the disk was just removed without preparing LVM, then just put the disk back in the server and reboot. If you intend to remove the device, first remove the disk from the volume group, then from the server.

Scenario 2:
If the disk is installed in the server, but still unknown, the LVM meta data may be missing. You need to restore the UUID for the device as displayed by pvscan, and then run vgcfgrestore to restore the LVM meta data. For example,

# pvcreate --uuid 56ogEk-OzLS-cKBc-z9vJ-kP65-DUBI-hwZPSu /dev/sdc
# vgcfgrestore ops
# vgchange -ay ops
# fsck /dev/ops/


NOTE: Make sure you use the correct UUID, as displayed by pvscan. Otherwise, the vgcfgrestore may fail.

Cause

A physical disk included in a volume group has been removed.

Additional Information

For more detailed information about recovering an LVM volume group, refer to Cool Solutions: Recovering a Lost LVM Volume Disk .

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:3803380
  • Creation Date: 01-Aug-2007
  • Modified Date:17-May-2021
    • SUSE Linux Enterprise Desktop
    • SUSE Linux Enterprise Server

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