[Xen-users] Trouble mounting domU logical volumes

[Liam Kirsher <liamk@xxxxxxxxxxx>]

Hi,

Has anyone gotten this working?  It might be that I just don't
understand LVM very well.

I'm having trouble mounting Xen image files.  I'm trying to follow the
instructions here:
http://fedoraproject.org/wiki/FedoraXenQuickstartFC5#head-1898c4d2e381f0407801069a6dcd61647d1c643c

I'm using default CentOS 5.0 install, which is Xen 3.0.3.  I thought
I should get it working first, before trying to upgrade to 3.[1 or 2?]. 
The virtual
domains I created using the Virt-Manager gui, and they are all CentOS 5.
Two use images and one uses a separate volume group (VolGroup01/LogVol00).
Below, I'm just trying to view the volumes in the image file of dom2, which
looks like this:
# Automatically generated xen config file
name = "dom2"
memory = "255"
disk = [ 'tap:aio:/var/lib/xen/images/dom2.img,xvda,w', ]
vif = [ 'mac=00:16:3e:1d:5f:3f, bridge=xenbr0', ]
vfb = ["type=vnc,vncunused=1"]
uuid = "5ca750c2-074c-321c-89f7-6e9609e965de"
bootloader="/usr/bin/pygrub"
vcpus=1
on_reboot   = 'restart'
on_crash    = 'restart'

The kernel in dom0 and dom2 /boot dir is vmlinuz-2.6.18-8.1.6.el5xen

The first time I tried, I used losetup with the image file, but it looks
like
kpartx will do this automatically without losetup:

kpartx -av /var/lib/xen/images/dom2.img
  loop0p1 : 0 208782 /dev/loop0 63
  loop0p2 : 0 2650725 /dev/loop0 208845

mount /dev/mapper/loop0p2 /mnt/dom2.p2
(apparently works)

vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "VolGroup01" using metadata type lvm2
  Found volume group "VolGroup00" using metadata type lvm2
  Found volume group "VolGroup00" using metadata type lvm2

(This seems wrong.  I don't think there should be two volume groups
with the same name, should there?  But, actually there are, because I
just used the default partitioning scheme in dom2, which sets up LVM.
I think this may be the problem.)

vgchange -ay VolGroup00
  2 logical volume(s) in volume group "VolGroup00" now active

(Does that mean the two in dom0:VolGroup00 or the supposed two new ones
in dom2:VolGroup00???)

lvs
  LV       VG         Attr   LSize  Origin Snap%  Move Log Copy%
  LogVol00 VolGroup00 -wi-ao  9.75G                             
  LogVol01 VolGroup00 -wi-ao  1.94G                             
  LogVol00 VolGroup01 -wi-a- 10.00G   

That VolGroup00 just looks like what I've got in dom0!  I tried to mount
the volume, per the how-to instruction

mount /dev/VolGroup00/LogVol00 /mnt/somedir

but only managed to mount the
volume I was on, not the one from the image. So.

I'm not going to say much more, because I think the problem is above
somewhere.  Can anyone point me in the right direction?  I was playing
around with this previously and really hosed the whole thing, so I don't
want to do that again!

Basically, I just want to create an image that I can use as a base to
create new domU's.  Well, I want to clone it as a backup.  So I really
need to be able to edit the images, and go back and forth easily between
file images and partitions.

Thanks in advance for your help!

Liam


-- 
Liam Kirsher
PGP: http://liam.numenet.com/pgp/


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