[linux-lvm] dmsetup says "Device does not exist", though it exists

[Christoph Pleger]

Hello,

I have a volume group with 20 logical volumes. Only the last one of 
these volumes has a strange problem with dmsetup, shown by these 
commands and output on the command line:

root at host:/home/linux# /sbin/dmsetup info -c -o name --noheadings 
/dev/vg/lv20
Device does not exist.
Command failed

root at host:/home/linux# lvdisplay -c /dev/vg/lv20
   /dev/vg/lv20:vg:3:1:-1:0:4194304:512:-1:0:-1:253:19

root at host:/home/linux# mount /dev/vg/lv20 /mnt
root at host:/home/linux# ls /mnt
lost+found data1 data2

That is, dmsetup says "Device does not exist" about a logical volume, 
though the volume exists and is operating normally. What is the possible 
problem here?

Regards
   Christoph