The Problem
LVM commands report Duplicate VG names. When vgdisplay is run to check for free space the following message is received:
# vgdisplay WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU
The Root Cause
Below are a few of the changes which can cause this issue:
1. Some changes have been made with the LVM configuration like adding a new LUN from SAN which was previously being used as LVM on another decommissioned system and has been added to the new system without proper cleaning from SAN side and has previous metadata.
2. A new VG was created using the same name which already exists on the system.
The “WARNING: Duplicate VG name” messages from LVM commands are an indication that multiple independent volume groups were discovered with the same name during scanning. This problem is not an indication of an improper filter and is not a result of using multipath. The warning message here specifically indicates that two volume groups exist with different UUIDs but the same name. Since LVM is unable to activate two volume groups with the same name, it chooses one (starting with the one which has creation_host matching the local hostname) and activates it.
Note: For information on a similar issue where a cloned storage device results in a duplicate VG with the same UUID, we need to follow the below steps and is different procedure.
vgimportclone [-n|--basevgname VolumeGroupName] [-i|--import] PhysicalVolume [PhysicalVolume...]
For example:
# vgimportclone --basevgname test_vg_snap /dev/loop2 /dev/loop3
This post is only specific to situations in which the duplicate VG contains a different UUID (i.e., is not a clone).
Diagnostic Steps
In these situations, usually, you will need to determine which device and/or UUID corresponds to the “original” volume group, and which corresponds to the “duplicate” volume group. You can not simply use vgdisplay or lvs to get information about each volume group, because they will be unable to determine which volume group you are requesting, and will just choose one of them to operate on. For example, to see the logical volumes in both test volume groups, it is not possible to just use lvs:
# lvs testvg2 WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU LV VG Attr LSize Origin Snap% Move Log Copy% Convert test_lv testvg2 -wi--- 2.00G
It only displays the LVs in the VG it chooses.
In order to display information about each individual volume group, we can use a filter on the command line. First, we must determine which devices are in each volume group:
# pvs WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU PV VG Fmt Attr PSize PFree /dev/xvda2 VolGroup00 lvm2 a- 14.88G 0 /dev/xvdb VolGroup00 lvm2 a- 9.97G 4.97G /dev/xvdc testvg1 lvm2 a- 5.00G 1020.00M /dev/xvdd testvg2 lvm2 a- 5.00G 3.00G /dev/xvde testvg2 lvm2 a- 5.00G 3.00G
We now know that xvdd and xvde host the two different testvg2 VGs. Let us take a look at each logical volumes to help us determine:
# lvs testvg2 --config 'devices { filter = [ "a|/dev/xvdd|", "r|.*|" ]}'
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
test_lv testvg2 -wi--- 2.00G
# lvs testvg2 --config 'devices { filter = [ "a|/dev/xvde|", "r|.*|" ]}'
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
test_lv testvg2 -wi-a- 2.00G
Once we know which of the duplicate VGs we would like to focus on, we can find the UUID for that VG:
# vgs -o +vg_uuid --config 'devices { filter = [ "a|/dev/xvde|", "r|.*|" ]}'
VG #PV #LV #SN Attr VSize VFree VG UUID
testvg2 1 1 0 wz--n- 5.00G 3.00G q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU
Now we can use this UUID in the steps in the below Solution section.
The Solution
The proper solution to this problem depends on the reason for the duplicate being presented. Read the Root Cause and Diagnostic Steps sections above for more information.
If the device containing the duplicate VG name was accidentally presented to this host (i.e., improper zoning), then simply unpresent it from the host. Once it is gone, the duplicate volume group problem will no longer be seen.
If a device was presented to the host that had a duplicate VG name to a volume already on this host, then the duplicate one will need to be renamed so as to not conflict. The renaming can be done using the UUID:
1. Determine the UUID for the volume group that you want to rename:
# vgs -o +vg_uuid WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU (created here) takes precedence over OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU (created here) takes precedence over OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 VG #PV #LV #SN Attr VSize VFree VG UUID VolGroup00 2 2 0 wz--n- 24.84G 4.97G KtK3ij-lkQH-tbB3-s74h-FYBl-73cu-jg86EX testvg1 1 1 0 wz--n- 5.00G 1020.00M oME1Wk-ftRi-qhQq-wQ6Z-eUo3-SNZw-chUfAx testvg2 1 1 0 wz--n- 5.00G 3.00G q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU testvg2 1 1 0 wz--n- 5.00G 3.00G OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5
2. Once you have the UUID you can then rename the Volume Group using vgrename:
# vgrename q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU testvg WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 (created here) takes precedence over q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU WARNING: Duplicate VG name testvg2: Existing q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU (created here) takes precedence over OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5 Volume group "testvg2" successfully renamed to "testvg"
3. Activate the new Volume Group.
# vgchange -ay testvg 1 logical volume(s) in volume group "testvg" now active
4. Verify the Volume Group.
# vgs -o +vg_uuid VG #PV #LV #SN Attr VSize VFree VG UUID VolGroup00 2 2 0 wz--n- 24.84G 4.97G KtK3ij-lkQH-tbB3-s74h-FYBl-73cu-jg86EX testvg 1 1 0 wz--n- 5.00G 3.00G q7jsuu-f3f8-mVVu-HpMm-FXdK-Xe3Y-d2nVfU testvg1 1 1 0 wz--n- 5.00G 1020.00M oME1Wk-ftRi-qhQq-wQ6Z-eUo3-SNZw-chUfAx testvg2 1 1 0 wz--n- 5.00G 3.00G OEsLyZ-ueap-D66F-6LEB-BKqC-A5B1-exlfZ5