lvm: creating a snapshot

[lee <lee@yagibdah.de>]

Hi,

how can I create a LVM snapshot of a VM?


root@heimdall:~# lvcreate -L 4G -s /dev/mapper/vg_guests-lv_jarl -n lv_snap_jarl /dev/mapper/vg_mydata
  Physical Volume "/dev/mapper/vg_mydata" not found in Volume Group "vg_guests"
root@heimdall:~#


There is no free space in 'vg_guests'.  The only free space is in
'vg_mydata'.

Can I create a snapshot over the network on disks an another machine?
Can I extend 'vg_guests', using the free space of 'vg_mydata'?  Or would
I have to shrink 'vg_mydata' to have free space to be able to extend
'vg_guests' to be able to create a snapshot?


I want to back up the VM without shutting it down.  If it can't
avoided, I could shut it down to take the backup.  In that case, how
would I copy the volume to get a useful backup file?

I think I wish I had used btrfs ...


-- 
Hallowed are the Debians!