[linux-lvm] creating a LVM ontop of a cryptated (ppdd) loop back device

[Jon Bendtsen]

I'm trying to cryptate my filesystems, and be able to take snapshots of
them.
I cannot get a snapshot of a cryptated LV to work (maybe because it is
readonly)
So i wanted to go the other way, and put the encryption in the bottom.
But, i cant create a VG ontop of a cryptated (ppdd) loop back device. It
works on a
unencrypted device. 

It pvcreates just fine, but when it comes to vgcreate, it says:
ve:/# pvcreate /dev/loop1
pvcreate -- physical volume "/dev/loop1" successfully created

ve:/# vgcreate vgt /dev/loop1
vgcreate -- no valid physical volumes in command line



Does anyone know any other encryption that works with LVM and/or allows
one to take snapshots?




JonB