Access GPT partitions on LVM volumes (map entry doesn't fit media)

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello everybody,

I have a Xen host on which various NetBSD VMs are installed. The VMs are 
in LVM volumes and are partitioned on the guest side with GPT. I would 
like to back up these LVM volumes as efficiently as possible when shut 
down. I would like to dump the ffs partitions in the LVM volumes from 
the host. However, I don't succeed so far.

Guest's GPT:
-------------

builder9# gpt show xbd0
	  start       size  index  contents
		  0          1         PMBR
		  1          1         Pri GPT header
		  2         32         Pri GPT table
		 34         30         Unused
		 64   33554432      1  GPT part - NetBSD FFSv1/FFSv2
   33554496         64         Unused
   33554560    8388608      2  GPT part - NetBSD swap
   41943168         64         Unused
   41943232  226492191      3  GPT part - NetBSD FFSv1/FFSv2
  268435423         32         Sec GPT table
  268435455          1         Sec GPT header
builder9#

Attempted access from the host:
-------------------------------

# gpt show /dev/mapper/rvg0-builder9
gpt: /dev/mapper/rvg0-builder9: map entry doesn't fit media: new start + 
new size < start + size
(22 + 7ffde < 40 + 2000000)


Do I have a mistake here, or is that not possible by design or is it a bug?

One side question came to my mind: Does anyone happen to know whether 
there is a kind of Partimage or Partclone for NetBSD besides g4u?


Best wishes
Matthias