Those will provide a multi-disk setup.

We desperately need linting here.. :(

show how to find the PV and resize it, that was omitted!

Let's use --absolute because it is less error-prone: I originally
thought the number there was the *final* disk space. But actually,
without --absolute, it is *added* to the existing disk space. This can
lead to fairly catastrophic results if we add too much disk space, as
reverting this requires a complex backup / restore procedure of the
VM, because grow-disk doesn't support shrinking disks.

Also mention this problem in the docs.

11:23:56 <weasel> I think this is something aurel came up with
11:24:08 <weasel> AIUI, it adds to the qemu command line,
11:24:26 <weasel> and it's a way to get randomness to VMs
11:25:45 <weasel> https://wiki.qemu.org/Features/VirtIORNG has some info on it

This failed in the gnt-chi cluster initialization.