PVs that are reused / reformatted as filesystems

Hi there,

I have a system on which a partition that was once a PV was recycled as a filesystem. Now, it has a valid ext3 filesystem on it, but also the PV signature appears to be there. So I can't start things up without liberal use of -P, and I can't seem to get anything except read-only operation.

IMHO The utilities should probably never try to treat any in-use kernel object as candidate for any kind of scanning or new use. ie, the userland equivalent of checking dev->kobj.kref.refcount == 0

Could someone please give me a fish (tell me how to un-jam my LVM) and maybe even teach the LVM drivers/utilities to fish as well?

Here's the command output;

samv:~# lvmdiskscan -v
  /dev/hda1 [       13.98 GB] LVM physical volume
  /dev/hda2 [       65.13 GB] LVM physical volume
  /dev/hda3 [       13.97 GB] LVM physical volume
  /dev/hda4 [        1.00 KB]
  /dev/hda5 [     1004.03 MB]
  /dev/hda6 [       17.72 GB] LVM physical volume
  0 disks
  2 partitions
  0 LVM physical volume whole disks
  4 LVM physical volumes
samv:~# mount | grep hda
/dev/hda3 on / type ext2 (rw,errors=remount-ro)
samv:~# vgchange -ay
  Failed to read VG data from PV (/dev/hda3)
  Failed to read VG data from PV (/dev/hda3)
  Unable to find volume group "Mirror"
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find all physical volumes for volume group samv.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find all physical volumes for volume group samv.
  Unable to find volume group "samv"
samv:~# vgscan -P
  Partial mode. Incomplete volume groups will be activated read-only.
  Reading all physical volumes.  This may take a while...
  Failed to read VG data from PV (/dev/hda3)
  Failed to read VG data from PV (/dev/hda3)
  Volume group "Mirror" not found
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Found volume group "samv" using metadata type lvm2
samv:~# vgchange -ay -P
  Partial mode. Incomplete volume groups will be activated read-only.
  Failed to read VG data from PV (/dev/hda3)
  Failed to read VG data from PV (/dev/hda3)
  Unable to find volume group "Mirror"
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  Couldn't find device with uuid 'PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE'.
  5 logical volume(s) in volume group "samv" now active
samv:~# mount /export/media
mount: block device /dev/mapper/samv-media is write-protected, mounting read-only
samv:~#

Sam Vilain, sam /\T vilain |><>T net, PGP key ID: 0x05B52F13
(include my PGP key ID in personal replies to avoid spam filtering)

Use pvscan / pvs -v to work out which devices you want to see and which you don't then change the filter in /etc/lvm/lvm.conf so you only see the right ones.

Alasdair

[email protected]

Thanks Alasdair.

It looks like my problem is actually deeper than I originally thought;

# vgdisplay -v foobar
[snip]
  --- Physical volumes ---
  PV Name               /dev/hda2
  PV UUID               weM5FG-L0Li-Ir7y-0B2z-MJoq-tvAg-C2Q19E
  PV Status             allocatable
  Total PE / Free PE    16672 / 0

  PV Name               /dev/hda1
  PV UUID               85M9M7-QsLh-dVKf-xfU3-ua4h-Ks4h-QGrMhu
  PV Status             allocatable
  Total PE / Free PE    3578 / 26

  PV Name               unknown device
  PV UUID               PtbIxo-EmRo-ML7J-yhqx-gglD-ZayH-X6tuWE
  PV Status             allocatable
  Total PE / Free PE    4535 / 4535

Hmm, now how can I use vgreduce on an read-only VG to remove an unknown PV?

# vgreduce --removemissing foobar

Gone.

Sam Vilain, sam /\T vilain |><>T net, PGP key ID: 0x05B52F13
(include my PGP key ID in personal replies to avoid spam filtering)

In future use pvremove to wipe a PV - the opposite of pvcreate. And first use vgreduce to remove it from its volume group.

Alasdair

[email protected]