We just made the change from oVirt to Proxmox, the reason is the topic for another post, but here i'm going to tell you how to export the VMs disc to a qcow2 file. The source VM disc is a LVM image
Prepare the VM
First you need to complete 2 task.
1. Delete network card association
This way you get the same interface you currently have. All you need to do is to empty the file /etc/udev/rules.d/70-persistent-net.rules.
2. Fill your disk with zeros
This tip is from Richard WM Jones (http://rwmj.wordpress.com/2010/10/19/tip-making-a-disk-image-sparse/) and the result is a thin provision qcow2 image. For every filesystem in your vm you need to run:
dd if=/dev/zero of=zerofile bs=1M
rm -rf zerofile
Ready to convert
1. Discover your VM LV association
Each disk of your vm is associated with a LVM volumen, so the first thing to do is to know which LV you need to export.
With the VM still running, connect to the Hypervisor where is running and run the following command:
virsh --readonly -c qemu:///system domblklist pbrunalab
Looking at the result you know that the vda disk is linked to some kind of device. Now you need to get the device:
ls -l /rhev/data-center/70ca7a78-b570-11e1-bcfe-2e18820c3a67/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/images/7e4c3ed3-73e6-44d8-8d21-efbb7818af86/e0c77de3-7589-43bc-bfdd-db11e11dab93
lrwxrwxrwx. 1 vdsm kvm 78 Feb 25 23:11 /rhev/data-center/70ca7a78-b570-11e1-bcfe-2e18820c3a67/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/images/7e4c3ed3-73e6-44d8-8d21-efbb7818af86/e0c77de3-7589-43bc-bfdd-db11e11dab93 -> /dev/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/e0c77de3-7589-43bc-bfdd-db11e11dab93
I you look carefully you already know that the Logical Volume is /dev/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/e0c77de3-7589-43bc-bfdd-db11e11dab93. No you can poweroff your VM.
2. Exporting to a qcow2 file
Now with vm not running and knowing the LV is time to export. This steps assume that in /mnt/export you had mounted a external device or a NFS share.
#Activate the LV
lvchange -ay /dev/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/e0c77de3-7589-43bc-bfdd-db11e11dab93
# Export to qcow2
qemu-img convert -p -O qcow2 /dev/e1537ba0-7d0f-4e4a-88b8-7f5698b2ceae/e0c77de3-7589-43bc-bfdd-db11e11dab93 /mnt/export/vm_disk-vda.qcow2