[linux-lvm] lvm2 confused about double UUID

Christian Kujau lists at nerdbynature.de
Mon Jul 27 00:21:34 UTC 2009

The subject says LVM is confused, but maybe it's me who is confused:

I once had a PV made from a single /dev/sdb and all was well. This sdb 
however was really a 2 disk RAID1 which is now split up, the system now 
sees both disks, sdb and sdc. Of course, sdb and sdc still have the same 

# blkid  | egrep 'sd[bc]'
/dev/sdb1: UUID="1O2Tkq-9Jy8-VfuZ-uzFh-1f6v-iVBD-hcK6Vq" TYPE="lvm2pv" 
/dev/sdc1: UUID="1O2Tkq-9Jy8-VfuZ-uzFh-1f6v-iVBD-hcK6Vq" TYPE="lvm2pv"

I decided to continue to use the VG that was set up on the PV, but since 
lvm comlained[0] about finding the same UUID on more than one device, I 
tried to instruct lvm to just use sdb for the VG:

# grep filter /etc/lvm/lvm.conf | grep -v \#
   filter = [ "r|^/dev/sdc1$|", "r|/dev/.*/by-path/.*|", \
              "r|/dev/.*/by-id/.*|", "a/.*/" ]

Now everything looks fine, no more lvm warnings, vg02 seems to use sdb1, 
exactly as I wanted:

# pvs
  PV         VG   Fmt  Attr PSize   PFree  
  /dev/sda2  vg01 lvm2 a-   111.67G   9.27G
  /dev/sdb1  vg02 lvm2 a-   931.46G 137.46G

But when I access vg02, I can clearly see I/O to/from sdc! I'd really like 
to use sdc for something else now that sdb is used for vg02, but I'm afraid to 
do something to sdc, as it still being used - although I don't know why.

Any ideas?


# lvm version
  LVM version:     2.02.26 (2007-06-15)
  Library version: 1.02.20 (2007-06-15)
  Driver version:  4.12.0
# uname -r
2.6.24-24-xen                      <-- Ubuntu/8.04

[0] e.g.
   Found duplicate PV 1O2Tkq9Jy8VfuZuzFh1f6viVBDhcK6Vq: using 
   /dev/disk/by-path/pci-fw1.1-scsi-0:0:0:1-part1 not /dev/sdb1
BOFH excuse #282:

High altitude condensation from U.S.A.F prototype aircraft has contaminated the primary subnet mask. Turn off your computer for 9 days to avoid damaging it.

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