[linux-lvm] LVM snapshot with Clustered VG

[Rob <lists@rarforge.com>]

Is there a way to convert an active LV on a clustered VG to an exclusive 
lock without deactivating it first? Or some way of taking a snapshot of 
a clustered LVM? I know I have read snapshots are not possible on CLVM, 
but the information seems outdated.

ha node1: /dev/vg_clus/logvol_clus
ha node2: /dev/vg_clus/logvol_clus

1) I can deactivate the the entire vg on node1 and node2 with 'vgchange 
-an vg_clus' and activate with -ay. Just stating cluster vg is working.

2) I can deactivate locally on node2 with 'vgchange -aln vg_clus' , it 
shows inactive on node2 and active still on node1
     - After deactivating, I cannot get exclusive lock on node1 with 
'vgchange -aey vg_clus'
       I get an error locking on node1

3) I can get exclusive an lock if I deactivate the VG on both nodes and 
then run 'vgchange -aey vg_clus' on either node. The lvcreate snapshop 
works, but again, it requires deactivating the vg, which isn't an option 
in production.


Setup:
  Centos 6.3 (current)
  cman+pacemaker dual primary drbd for HA KVM w/ live migration
  disk: lvm -> drbd -> clvm -> kvm virt

Currently I am taking a lvm snapshot of the drbd lvm backing device, but 
it's not ideal ( as there are other issues )

Thanks for the time!

-Rob