libvirt users - Apr 2014 - Advice request for building a centralized vm disk provider server

Hello again, sorry for mailing in so short time but I have another question
about live migration.
>From redhat documentation I see that the storage for a VM which has to be
migrated has to be shared throught some mechanism and I have chosen iscsi.

Anyway I now would need a way to dinamically create a new virtual machine
and so a virtual hard disk, note that this vm will have to be migrated too.

I though about this solution: I would share an HUGE iscsi target, this
target is a logical hard drive containing many disk images which would be
the VM's hard drives. I can easily clone a vm by making a simple file copy
of a vm disk.

This would allow me to create a VM by specifying a path like <iscsi target
path>/disk1.img.

I have two problems:
1)how to get an unique <iscsi target path>? On my phisical host it is
mounted as a random uuid in the /media folder.
2)will migration work with a <file> instead of a <device> as hard
disk
field?

If you have any better solution, even involing the change from iscsi to
another technology, you are free to propose it to me.

Sorry for bothering,
Pasquale