11.04->11.10 KVM guest console problem

[Serge Hallyn]

On 12/08/2011 11:17 AM, James Crow wrote:
> Hi all,
>
> I am learning my way around with KVM. I have a Dell PowerEdge R410 server
> that I installed 11.04 amd64 on. I then created two guests and installed
> 10.04.3 amd64 on each. Everything was working up to this point.
>
> Today, I decided to try the upgrade to 11.10 for the host OS. I did a
> virsh save<guest-name>  <save-file>  for each guest and then upgraded the
> host OS.
>
> The upgrade seemed to progress without incident. I let the host restart
> during the upgrade and once it was done I was able to SSH back in to the
> host.
>
> I should note that my home directory on the host is encrypted and I have
> setup SSH with keys so I can login to the host from my desktop without
> entering a password. When I login this way my home directory on the host
> does not get mounted.
>
> After the upgrade I connected from my desktop with the GUI virtual machine
> manager and saw that both of my guests were running. Great!, I thought. The
> problem is I am now unable to connect to the console for either guest. If I
> try to open the console from the GUI app the window display "Connecting to
> graphical console for guest." I have waited over an hour and the message
> stays the same. I am also unable to connect to the guest from within virsh
> through a SSH session.

By 'console' do you mean the serial console, or vnc?  Are you able to 
ssh into the guests?  Do they respond to a ping?

> libvirt appears to be working because I can run virsh from SSH and connect
> with the GUI manager. I am able to suspend/save/start the guest. I am
> simply unable to view their consoles.
>
> Any ideas appreciated.

(Below is assuming that the VMs are not running right,  you can't ping 
them.  If you can ping them, then likely libvirt is just not hooking up 
the serial console right)

If I had to guess, I'd say that by saving and restoring - rather than 
shutting down and later restarting - the guests, you ran into an 
incompatibility in the save/restore image across qemu versions.  That's 
just a guess, though.

So long as you still have the <save-file> for each guest, you could try 
starting the guest up clean ('virsh start guest-name') and see if that 
comes up fine.

Another thing you could try would be to create a 10.04 chroot (using 
debootstrap) on your host, chroot into it, install qemu-kvm and libvirt,
copy over the guest config files, and see if you can connect to the 
consoles from there.

I'm tempted to ask for guest .xml files, but at that point we'd be 
better off talking in a launchpad bug.

-serge