Re: [Xen-users] Trouble mounting domU logical volumes

[Liam Kirsher <liamk@xxxxxxxxxxx>]

Well, I answered my own question.  I tested it out with a fresh install,
and during the installation process named the VolGroup and LogVolumes
something different from the default.  That was the key.

So, I wanted to rename it. First problem was that vgrename kept giving
me "permission denied" until I changed the selinux policy.
The second problem, was that after changing the VolGroup name the domU
kernel wouldn't boot. I could mount the VolGroup from dom0 fine. It
turned out the VolGroup name in /dev was still the old one.  That's as
far as I got.

Liam wrote:
> 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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