Description of problem:

If you have an exported mirrored LVM DG that is missing a mirror it is impossible to import the DG.  Tested in 5.8 and 6.3... See following reproducer:

[root@ll-chsystest03 logs]# dd if=/dev/zero of=loop0 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 0.583542 s, 1.8 GB/s

[root@ll-chsystest03 logs]# dd if=/dev/zero of=loop1 bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 0.593067 s, 1.8 GB/s

[root@ll-chsystest03 logs]# losetup /dev/loop0 /logs/loop0

[root@ll-chsystest03 logs]# losetup /dev/loop1 /logs/loop1

[root@ll-chsystest03 logs]# pvcreate /dev/loop0

[root@ll-chsystest03 logs]# pvcreate /dev/loop1

[root@ll-chsystest03 logs]# vgcreate TRASHME /dev/loop0 /dev/loop1

[root@ll-chsystest03 logs]# lvcreate --contiguous n --alloc normal -m 1 -n trashme -L500m TRASHME /dev/loop0 /dev/loop1
  Logical volume "trashme" created

[root@ll-chsystest03 logs]# lvs
  LV      VG      Attr     LSize   Pool Origin Data%  Move Log          Copy%  Convert
  trashme TRASHME mwn-aom- 500.00m                         trashme_mlog 100.00
  logs    vg0     -wi-ao-- 520.69g
  root    vg0     -wi-ao--  14.00g
  tmp     vg0     -wi-ao--   2.00g
  var     vg0     -wi-ao--   6.00g


[root@ll-chsystest03 logs]# vgs
  VG      #PV #LV #SN Attr   VSize   VFree
  TRASHME   2   1   0 wz--n-   1.95g 988.00m
  vg0       1   4   0 wz--n- 542.69g      0


[root@ll-chsystest03 logs]# vgchange -an TRASHME
  0 logical volume(s) in volume group "TRASHME" now active

[root@ll-chsystest03 logs]# vgexport TRASHME
  Volume group "TRASHME" successfully exported

[root@ll-chsystest03 logs]# losetup -d /dev/loop1

[root@ll-chsystest03 logs]# vgs
  Couldn't find device with uuid utPEIg-JC7U-4xP0-BXsu-oRl9-IjHS-4oyEGQ.
  VG      #PV #LV #SN Attr   VSize   VFree
  TRASHME   2   1   0 wzxpn-   1.95g 988.00m
  vg0       1   4   0 wz--n- 542.69g      0


[root@ll-chsystest03 logs]# vgimport TRASHME
  Couldn't find device with uuid utPEIg-JC7U-4xP0-BXsu-oRl9-IjHS-4oyEGQ.
  Cannot change VG TRASHME while PVs are missing.
  Consider vgreduce --removemissing.

[root@ll-chsystest03 logs]# vgreduce  TRASHME --removemissing --force
  Couldn't find device with uuid utPEIg-JC7U-4xP0-BXsu-oRl9-IjHS-4oyEGQ.
  Unable to determine mirror sync status of TRASHME/trashme.
  Volume group "TRASHME" is exported
  Failed to lock trashme

The "Failed to lock" problem is where the issue comes in.  "vgreduce" cannot fix the problem because it can't get a lock on an exported diskgroup, and vgimport can't import the diskgroup since its "broken".  Catch-22.



Version-Release number of selected component (if applicable):

RHEL5.8 and RHEL6.3

How reproducible:


See above


Additional info:

Workaround #1

#this will give me the pv uuid
vgdisplay  --partial --verbose

cd /etc/lvm/backup

There should be a file there called TRASHME

get a pv same size as what was there before, your are simulating

losetup /dev/loop1 /logs/loop1

now restore the pv with same uuid and meta data from our /etc/lvm/backup/TRASHME file
pvcreate --restorefile TRASHME --uuid mBR3gH-V90u-yOOk-V4BL-Llg0-UFH1-MfKbib /dev/loop1 -ff

[root@localhost backup]# vgimport TRASHME
  Volume group "TRASHME" successfully imported

Workaround #2

You could hand edit the backup file of the LVM metadata (generally found in /etc/lvm/backup/<VG NAME>).  You would simply need to remove the 'EXPORTED' flag wherever it is found and then run vgcfgrestore