Unable to remove LVs

Hi,

LVM 2.02.39-7 on Debian Lenny 64 bit with Xen 3.2-1

I have a few LVs that I can't get rid of:

server1:/# ls -al /dev/mapper/*oa*
brw-rw---- 1 root disk 254,  7 2011-07-22 19:40 /dev/mapper/d-pdc.oa.c
brw-rw---- 1 root disk 254, 78 2011-10-30 13:04 /dev/mapper/d-pdc.oa.cp1
server1:/# kpartx -l /dev/mapper/d-pdc.oa.c
d-pdc.oa.c1 : 0 71103627 /dev/mapper/d-pdc.oa.c 63
server1:/# kpartx -d /dev/mapper/d-pdc.oa.c
server1:/# kpartx -d /dev/mapper/d-pdc.oa.c1
failed to stat() /dev/mapper/d-pdc.oa.c1
server1:/# lvs | grep oa
  pdc.oa.c         d    -wi-ao  37.00G                                    

There were a couple of other open LVs that I could successfully delete using the method described above but this one seems to be a bit harder to convince. The LV surely isn't open by anything I can identify (not mounted etc), but the kernel seems to think otherwise.

Any suggestions?

kind regards,
Jan

This should have removed the <name>p1 partition map previously created by kpartx -a.

The kpartx command expects the base device as its argument (as you gave in the previous command). This should be "/dev/mapper/d-pdc.oa.c" (the '1' is the partition index and the 'p' is the separator).

The partition map has a 'p' separator - d-pdc.oa.cp1 - the correct command is:

kpartx -d /dev/mapper/d-pdc.oa.c

The LV is still showing as active and open here. You should be able to remove it with lvremove d/pdc.oa.c or shut it down with vgchange/lvchange after correctly removing the kpartx mapping.

If it still shows as open you may want to look at the output of "dmsetup ls --tree" to see if there are other device-mapper devices using it and make sure that it's not mounted anywhere.

Regards,
Bryn.

Hi Bryn,

# kpartx -d /dev/mapper/d-pdc.oa.c
# kpartx -l /dev/mapper/d-pdc.oa.c
d-pdc.oa.c1 : 0 71103627 /dev/mapper/d-pdc.oa.c 63
# lvs | grep oa
  pdc.oa.c         d    -wi-ao  37.00G      

# lvremove d/pdc.oa.c
  Can't remove open logical volume "pdc.oa.c"
# lvchange -a n d/pdc.oa.c
  LV d/pdc.oa.c in use: not deactivating

# dmsetup ls --tree
d-pdc.oa.cp1 (254:78)
 └─d-pdc.oa.c (254:7)
    └─ (8:11)

I'm positive it's not mounted anywhere.

Any advice how to proceed from here?

kind regards,
Jan

It's possible kpartx is getting confused and is refusing to remove the maps if they still exist after running this command.

You can try to remove the device manually with dmsetup:

dmsetup remove d-pdc.oa.cp1

If this succeeds then you can proceed to deactivate the lv/vg. If it fails then there is something still using the device and you'll need to figure out what it is to get rid of the devices.

Regards,
Bryn.

That seems to be the case:

# vgcreate d /dev/loop0
  Volume group "d" successfully created
# lvcreate -n pdc.oa.c -L 4m d
  Logical volume "pdc.oa.c" created
# fdisk /dev/d/pdc.oa.c
[...]
# kpartx -l /dev/mapper/d-pdc.oa.c
d-pdc.oa.c1 : 0 8191 /dev/mapper/d-pdc.oa.c 1
# ls /dev/mapper/d-pdc.oa.c*
/dev/mapper/d-pdc.oa.c  /dev/mapper/d-pdc.oa.cp1
# kpartx -d /dev/mapper/d-pdc.oa.c
# kpartx -l /dev/mapper/d-pdc.oa.c
d-pdc.oa.c1 : 0 8191 /dev/mapper/d-pdc.oa.c 1
# ls /dev/mapper/d-pdc.oa.c*
/dev/mapper/d-pdc.oa.c  /dev/mapper/d-pdc.oa.cp1

It does the right thing if you specify the partition separator on the command line:

# kpartx -d -pp /dev/mapper/d-pdc.oa.c
# ls /dev/mapper/d-pdc.oa.c
/dev/mapper/d-pdc.oa.c

Regards,
Bryn.

Kia ora Bryn,

It seems I'm being bitten again by this. Last time you kindly helped me resolve this issue on a Debian Lenny (kernel 2.6.26-2-xen-amd64, lvm 2.02.39-7, kpartx 0.4.8-14+lenny2).

This time it's a slightly older system (Debian Etch, kernel 2.6.18-6-xen-amd64, lvm 2.02.06-4eth1) but in a rather remote location (at sea). The system is rock solid otherwise and upgrading is quite an undertaking so if at all possible I hope to be able to resolve this issue without upgrading.

Any advice you can offer is much appreciated.

kind regards,
Jan

# lvs
  LV         VG   Attr   LSize   Origin Snap%  Move Log Copy%
  xm.dt1     d    -wi-a-   8.10G                             
  xm.dt1old  d    -wi-a-   8.10G                             
  xm.dt2     d    -wi-ao  12.00G                             
  xm.fms     d    -wi-ao  12.10G                             
  xm.w2k     d    -wi-ao  12.10G                             
  xm.wxp     d    -wi-ao   8.10G                             
  xm.wxp-eng d    -wi-ao   8.10G                             
  xm.wxp-ro  d    -wi-ao   8.10G                             

# kpartx -l /dev/mapper/d-xm.dt1old
d-xm.dt1old1 : 0 16980642 /dev/mapper/d-xm.dt1old 63
# kpartx -d -pp /dev/mapper/d-xm.dt1old
# kpartx -l /dev/mapper/d-xm.dt1old
d-xm.dt1old1 : 0 16980642 /dev/mapper/d-xm.dt1old 63

# ls -al /dev/mapper
total 0
drwxr-xr-x  2 root root     620 2012-09-17 23:17 .
drwxr-xr-x 19 root root    5140 2012-09-17 23:17 ..
crw-rw----  1 root root  10, 62 2044-01-30 07:04 control
brw-rw----  1 root disk 254, 21 2044-01-30 07:05 d-xm.dt1
brw-rw----  1 root disk 254, 12 2044-01-30 07:05 d-xm.dt1old
brw-rw----  1 root disk 254, 22 2044-01-30 07:05 d-xm.dt2
brw-rw----  1 root disk 254, 15 2012-09-17 23:25 d-xm.fms
brw-rw----  1 root disk 254, 24 2044-01-30 07:05 d-xm.fms1
brw-rw----  1 root disk 254, 18 2044-01-30 07:05 d-xm.w2k
brw-rw----  1 root disk 254, 25 2044-01-30 07:05 d-xm.w2k1
brw-rw----  1 root disk 254, 23 2012-09-17 03:40 d-xm.wxp
brw-rw----  1 root disk 254, 29 2044-01-30 07:05 d-xm.wxp1
brw-rw----  1 root disk 254, 19 2044-01-30 07:05 d-xm.wxp--eng
brw-rw----  1 root disk 254, 27 2044-01-30 07:05 d-xm.wxp--eng1
brw-rw----  1 root disk 254, 13 2044-01-30 07:05 d-xm.wxp--ro
brw-rw----  1 root disk 254, 20 2044-01-30 07:05 d-xm.wxp--ro1

Omiha Systems Ltd
NEW ZEALAND
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Hi Bryn,

I managed to figure it out.

dmsetup remove /dev/mapper/d-xm.dt1old1

removes the partition.

Then I can remove the LV.

Sorry to bother you.

Jan