PVE, easily extend a small DRBD Volume

Hi to all

I had read and tested the PVE wiki of DRBD, but now i want something more precise: a easy way for get that when i want, i can extend the DRBD volume and adjacent layers (if are necessary) with VMs running online or offline (preferably online)

This consult about of how do it is because if i have a big disk, i don't want put my DRDB volume in the big LVM partition due to that the verify online the DRBD resource (into the both nodes) delay long time. Then, my target is to have a small DRBD resource, and when i need enlarge the virtual disk of the VM, first enlarge the DRBD volume and/or adjacent layers. Being well, my verification online of DRBD resource will be more fast (and obviously I will have free space without use on my HDD).

DRBD have a explicacion very simple about of this:
http://www.drbd.org/users-guide/s-resizing.html

But i don't know how configure all these layers (including DRBD) in PVE, for that all this works very well, nor know the extra manual process that i have to do (enlarge partition, LVM, DRBD, whatever) for that i finally can resize the virtual disk into the PVE GUI.

Also, i forgot say that i don't want LVM partitions nested

If somebody can help me, i will be very grateful
Note: i don't need explains step by step, only the ideas for do it, but please, not advise me if you are unsure.

Best regards
Cesar