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The Xen bridge in Oracle VM Server 3.0.3

by Laurens van der Starre on March 4, 2012 · 7 comments

Switching from Oracle VM Server 2.2 to 3 is a big step. One of the reasons is because there is no upgrade path, only a complete fresh installation process. However, it can be worth while, for example the OVA support is pretty neat. Hardware support is also said to be better, something that really speaks to my mind after some issues on my VM 2.2 install.

So if you’re upgrading to VM Server 3 from a version 2 installation, there might be a few things to keep in mind (especially if you have a single node instance like me). One thing is that the installer doesn’t create a ocfs2 partition by default. If you’re happily “next-ing” through the installer you’ll miss something when the machine boots 😉 During the installation, review the partition layout, and don’t forget to add the ocfs2 partition (like me).

Secondly, although the hardware support is better, I noticed that the network is not completely set up out of the box. When I was done migrating some of my “2.2 VMs” on the new 3.0.3 installation, I couldn’t get them to start:

Error: Device 0 (vif) could not be connected. Could not find bridge device xenbr0

It seems that (at least in my case) the Xen bridge wasn’t started. Checking with

$ brctl show
bridge name	bridge id		STP enabled	interfaces

indeed shows no network bridge. This is a bit worrying because it should start automatically when the Xen deamon (xend) is started. Before we start manually adding network interfaces, bridges and adding routes: there is a script for that.

Run it as root on dom0:

cd /etc/xen/scripts
./network-bridge start

will add the bridge and pbond0 interface!

$ brctl show
bridge name	bridge id		STP enabled	interfaces
bond0		8000.f46d0400dff8	no		pbond0

I hacked the following at the end of /etc/rc.local to make it start at boot:

cd /etc/xen/scripts
./network-bridge start
./network-bridge status

It works after a reboot, but my Spider-Sense is telling me that there must be some nicer solution. If you happen to be a Xen expert, please leave a comment below 😉

Note that the bridge name has changed since v2.2. If you’re familiar with VM Server 2.2: edit the vm.cfg to represent the correct bridge name after migration of your VMs.

The Xen bridge in Oracle VM Server 3.0.3, 4.0 out of 5 based on 1 rating
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{ 7 comments… read them below or add one }

Avi Miller March 10, 2012 at 11:23 pm

Oracle VM 3.0 is completely configured via the Manager UI now, so the bridges are configured by the Networking section of the Manager. In fact, once you’ve configured your Networks in the UI, the ovs-agent process automatically validates if the bridge is available on the servers prior to start or live-migration of a guest, and if not will create it for you.

So, I strongly recommend you use the Manager UI to do this configuration.

Reply

Laurens van der Starre March 11, 2012 at 9:24 am

Yes, you’re right. However, in my opinion a fresh install should at least have a bridge preconfigured. In a DEV environment it is not uncommon to run the VM Manager in a guest OS on the server. This might cause a “chicken or egg” situation…?

Reply

Avi Miller March 12, 2012 at 11:38 pm

It’s too difficult to try and install Oracle VM Manager (currently) as a guest of the server it’s trying to manage, because not only do you need the Manager to setup the networking, but also the storage.

So, the recommended path if this is really what you want to do is either to use the Oracle VM Manager template for VirtualBox on your desktop instead, or use that as a base and then install a new Manager inside a guest with the SAME UUID as the Manager inside the VirtualBox images and move your data across.

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Avi Miller March 10, 2012 at 11:25 pm

Also note that if you have Oracle VM support, there is a migration script that can migrate your 2.2 install to 3.0 for you. It rewrites the VM configuration from the old xenbrX bridges to the new UUID-named bridges in 3.0 as well as rewriting the file paths for the new 3.0 storage repository system.

Reply

Laurens van der Starre March 11, 2012 at 9:30 am

This is cool. Do you have the support ID for this? I can’t really find it at the moment on the Support site.

Reply

Avi Miller March 12, 2012 at 11:41 pm

Repository Migration from Oracle VM Release 2 to Oracle VM Release 3 (Doc ID 1366216.1)

Reply

Das December 2, 2013 at 9:41 am

I have a similar problem where I want to setup a VM server with another different server in the same Box. But not able to assign a static IP not even I am able to create such thing.
Any idea ?

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