[linux-lvm] Suggestion for LVM

[Torben Viets]

Hello,

first I want to say I like your project and thank everyone, who is 
involved in this project, you made good work.

But I have one problem with the LVM, I post it hear for some days 
("LVM-Snapshot + dm_crypt"), the problem was that I can't made a 
snapshot of a dm-crypted LVM, then it creates the snapshot, but nothing 
works. And if I encrypt it on the device /dev/mapper/mp3 then I can't 
use the Snapshot function because lvcreate can't locate the volume group 
/dev/mapper, what logical.

Now my suggestion for a new LVM version is, couldn'tyou made it possible 
that lvcreate get an alternative path for the snapshot volume, now a 
example how i thought it could work.

pvcreate /dev/md0 //creating a physical volume
vgcreate /dev/data //create a volumegroup
lvcreate -L 8G -nmp3-crypt /dev/data //creating a volume group, 
everything on this will be crypted
cryptsetup create mp3 /dev/data/mp3-crypt //creating a encrpted device, 
I use cryptsetup because I don't know how dm_setup works :D
mkfs.xfs -f /dev/mapper/mp3
mount /dev/mapper/mp3 /mnt/mp3
cp -r *  /mnt/mp3

if I now make a
lvcreate -s -nsnap /dev/mapper/mp3
then I get a error Message (volume group mapper doesn't exit)
now my idea was that I give lvcreate on which vg the snapscho schould 
create for example
lvcreate -s -nsnap /dev/mapper/mp3 --snap-vg /dev/data/mp3-snap

is this possible to patch or is there a good reason why this doesn't 
work, I try to make it my self but my programming skills are not good 
enough to do this. Could some please made it, or is this senseless.

I hope you understand my problem.

greetings
Torben Viets