I am doing this on proxmox
1) login to the proxmox server
2) cd to the disk you need to expand
[box] cd /var/lib/vz/images[/box]
3) Increase the disk size
[box] qemu-img resize diskimage.zzz +[size in GB you want to expand]G[/box]
4) boot your VM with gparted or partition magic live iso
5) expand the volume to the new size
6) reboot the VM normally
7) run command
[box]pvdisplay[/box] 8) note the "VG NAME" 9) run
[box]lvextend -L+[size in GB you want to expand]G /dev/{insert VG NAME]/root[/box] 10) Done!