libvirt users - Sep 2011 - changue bridge name, libvirt refuses to take new name

hi all,

(this events ocurred before my previous mail about the uuid incident)

so, I installed a vm
host: rhel6
guest: centos6
network: bridge (br0, eth1 as slave)

but then, I changed the name of the bridge from br0 to br1
(because br1<->eth1 seems pretty than br0<->eth1)

so:

- mv /etc/sysconfig/network-scripts/ifcfg-br0
/etc/sysconfig/network-scripts/ifcfg-br1

- edited /etc/sysconfig/network-scripts/ifcfg-br1
  change DEVICE=br0 by DEVICE=br1

- edited /etc/sysconfig/network-scripts/ifcfg-eth1 and
changed the line BRIDGE=br0 to BRIDGE=br1

- edited /etc/libvirt/qemu/rmdev2.xml and changed the line <source
bridge='br0'/> to <source bridge='br1'/>

- service network restart
  <aside note>
    boom! lost connection to the server
    I had to go to server location (a few miles) by car
    because the network restart didn't stop br0 because thera was no script
br0
    and when br1 started produced a collision
  </aside note>

- service libvirtd restart

# brctl show
bridge name     bridge id               STP enabled     interfaces
br1             8000.e41f13ba6e1a       no              eth1
virbr0          8000.5254003a3124       yes             virbr0-nic

# virsh -c qemu:///system start rmdev2
error: Failed to start domain rmdev2
error: Failed to add tap interface to bridge 'br0': No such device

there *nothing* 'br0' in /etc in the system (I grepped it),
why is looking for br0 instead of br1 ?


I ended up undefining rmdev2, installing a new guest called rmdev2
using br1, and that was when I got the
error: operation failed: cannot restore domain 'rmdev2' uuid
9e9ea633-9691-f3d6-64da-ae9c8b3e5810 from a file which belongs to
domain 'rmdev2' uuid 4f425d14-335b-0adc-11af-06e503c6b54d

yes, I was ready to fire the house and leaving for better places...


thanks,
/sergio

On 09/26/2011 10:42 AM, Sergio A. Kessler wrote:
> - edited /etc/libvirt/qemu/rmdev2.xml and changed the line<source
> bridge='br0'/>  to<source bridge='br1'/>
Wrong.  You should not be directly editing anything under /etc/libvirt, 
but instead should be using 'virsh edit rmdev2' to make those changes. 
It may be because you went behind libvirt's back that your edits were 
not recognized, and that you had to end up undefining and re-creating a 
new guest before you got this to work the way you wanted.
> # brctl show
> bridge name     bridge id               STP enabled     interfaces
> br1             8000.e41f13ba6e1a       no              eth1
> virbr0          8000.5254003a3124       yes             virbr0-nic
>
> # virsh -c qemu:///system start rmdev2
> error: Failed to start domain rmdev2
> error: Failed to add tap interface to bridge 'br0': No such device
>
> there *nothing* 'br0' in /etc in the system (I grepped it),
> why is looking for br0 instead of br1 ?
One other thing to check, although I'm not sure it matters in your case 
(since you said that creating a new domain worked): when modifying 
network information, you may also need to modify libvirt's notion of the 
network, via such commands as 'virsh net-list' and 'virsh
net-edit'.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org