[linux-lvm] pvcreate succeeds but vgcreate cannot read label

[Malcolm Scott]

When I run pvcreate on a partition, it seems the PV label is successfully 
written to the partition, but vgcreate cannot then read this label in order 
to incorporate this new PV into a new VG.

mas90 at neptune ~ $ sudo pvcreate /dev/hda6
   Physical volume "/dev/hda6" successfully created

mas90 at neptune ~ $ sudo vgcreate neptune_vg /dev/hda6
   No physical volume label read from /dev/hda6
   /dev/hda6 not identified as an existing physical volume
   Unable to add physical volume '/dev/hda6' to volume group 'neptune_vg'.

mas90 at neptune ~ $ sudo dd if=/dev/hda6 bs=1k count=1 | hexdump -c
1+0 records in
1+0 records out
0000000  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
*
0000200   L   A   B   E   L   O   N   E 001  \0  \0  \0  \0  \0  \0  \0
0000210   #   - 335   }      \0  \0  \0   L   V   M   2       0   0   1
0000220   h   2   W   4   r   k   w   f   t   N   B   j   s   h   W   f
0000230   M   r   s   a   E   O   f   q   3   M   U   J   S   Z   w   z
0000240  \0   n   ) 342 004  \0  \0  \0  \0  \0 003  \0  \0  \0  \0  \0
0000250  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
0000260  \0  \0  \0  \0  \0  \0  \0  \0  \0 020  \0  \0  \0  \0  \0  \0
0000270  \0 360 002  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
0000280  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
*
0000400
1024 bytes (1.0 kB) copied, 0.009396 seconds, 109 kB/s

What could cause this?

The system is running Ubuntu Edgy, with the following versions:

mas90 at neptune ~ $ sudo lvm version
   LVM version:     2.02.06 (2006-05-12)
   Library version: 1.02.07 (2006-05-11)
   Driver version:  4.6.0

mas90 at neptune ~ $ uname -a
Linux neptune 2.6.17-10-generic #2 SMP Tue Oct 10 19:45:28 UTC 2006 i686 
GNU/Linux

Please CC me on replies as I am not on this mailing list.

Many thanks.

-- 
Malcolm Scott
Research Associate, TINA project
University of Cambridge Computer Laboratory