On 03/26/2013 02:13 PM, Björn Nadrowski expounded in part:

So, should I rewrite the beginning of the device with the dd command?

What then?

Thanks a lot for all your help!

You could try the dd, if it has a good chance of restoring the device to before the pvcreate. I don't know offhand how much of a PV pvcreate overwrites. Hopefully, an LVM guru can chime in. Before doing pvcreate, things like vg_scan -v should give a clue as to whether knoppix is even looking at md127. You might need to tweak the device filter in lvm.conf for knoppix.