Moved a VM server, now VMs can't talk

[davesill]

I'm running Ubuntu 9.10 AMD64 with KVM and several VMs running the same
OS. Everything was running fine and the VMs were using the host's
network via bridging. The decision was made to move the server to
completely different network. I shut it down, the system was moved and
hooked up, and I got it up on the new network pretty easily--just
modified /etc/network/interfaces and /etc/resolv.conf. No networking
problems at all.

Then I fired up virt-manager, powered up one of the VMs, and made the
same kinds of changes. It's not talking beyond the VM server. I can ping
the host, but can't ping the gateway. "tcpdump -i eth0" shows plenty of
traffic.

Any idea what's going on?

[Rubberman]

Unfortunately it isn't quite so simple. You needed to export your old VM and then import it on the new system. The original VM is "bound" to the original host. The import/export process allows the VM to be moved to another host. Since you didn't do that, things get murky...

[davesill]

Why would I need to import/export if the VMs are staying on the same host?

And given that I didn't do that, how can I get the VMs running now?

[Rubberman]

From your original post I assumed that you at least moved the VM pseudo-disc files to another directory? If so, that reequires an export and then reimport in the new location in many cases. In any event, you need to look at the KVM documentation do determine how to move VM's so that all the network and other settings are kept intact. I use VirtualBox and you do need to perform the export/import steps I mentioned.

[davesill]

No, I didn't reorganize anything on the VM host. Beside physically relocating the system, the only thing that changed was the network to which it was attached.

I reconfigured the networks on the VMs after the move, and they see network traffic but they can't talk.