WARNING: Duplicate VG name

Environment

• Red Hat Enterprise Linux
• LVM2

Issue

• LVM related commands are spewing warnings about duplicate VGs

WARNING: Duplicate VG name vg_name: abCDe4-Ab9C-DeFG-a9bc-DEfG-LmNo-Pq0RsT (created here) takes precedence over aBcd8a-76ab-aBcd-EFge-9ab0-a7Bc-AbCddE

• One or more of my Volume Groups appears to have gone missing and I'm getting Duplicate VG warnings
• After cloning my disk I'm getting warnings from LVM commands regarding Duplicate VG names
• After importing disks from another machine, I'm getting warnings that the Volume Group has been duplicated

Resolution

1. Verify you are getting the Duplicate VG name warning from your commands

# lvs vgname
  WARNING: Duplicate VG name vgname: JwG3LS-u7aQ-a96s-nKuL-aWVx-iKaV-uc2pJ0 (created here) takes precedence over Cd1BG6-2Mrn-FW9r-qnjA-YKsx-YMA1-pfl4v2
  LV       VG         Attr   LSize   Devices                
  lvol     vgname     -wi-ao 179.95G /dev/emcpowerb1(0)     

2. Check the output of pvs to see which disks currently belong to the volume group

# pvs -o pv_name,vg_name,pv_uuid
  PV                       VG          PV UUID                               
  /dev/emcpowerb1          vgname      2tLome-P2nz-IBAd-gsKi-LN0c-f39v-yZvTe2
  /dev/emcpoweru1          vgname      ZCB3Wq-JSR5-RRPx-oOLN-f6bv-vzx0-mGmnrF

3. Check the backup metadata for your volume group to verify the correct PV UUID of your disk. This file should be located under /etc/lvm/backup/<vgname>

# grep device etc/lvm/backup/vgname -B1 | grep id
			id = "2tLome-P2nz-IBAd-gsKi-LN0c-f39v-yZvTe2"

4. Use the vgimportclone against the disk that is not in the backup metadata

# vgimportclone --basevgname vgname_clone /dev/emcpoweru1

• If the output from pvs shows identical disks, the vgimportclone command can be run on either disk.

5. Verify the error is gone and we now see two different volume groups

# lvs
  LV       VG               Attr   LSize   Devices                
  lvol     vgname           -wi-ao 179.95G /dev/emcpowerb1(0)     
  lvol     vgname_clone     -wi-a- 179.95G /dev/emcpoweru1(0)     

Root Cause

• LVM volume groups are defined using metadata on the header of the disk. If two disks have different metadata, but identical volume group names, the warning will be displayed
• Renaming a volume group to a volume group that already exists will cause this issue
• Importing a volume group from another system that has the same name will cause this issue
• Creating a hardware clone of your LUN can cause this issue

This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.