[virt-tools-list] Re: [libvirt] RHEL 5 with Xen - changed IPs and now weirdness

[Daniel P. Berrange]

On Wed, Oct 21, 2009 at 11:36:50AM -0400, Denny Snyder wrote:
>    Hi all,
> 
>    I had installed RHEL 5 x86_64 with virtualization right off the bat. 
>    Everything ran beautifully with two Xen guests (also RHEL 5.)  All 3 IPs
>    (host and 2 guests) were in the same subnet.
> 
>    Then I had to change all the IP addresses to a different subnet (but again
>    all 3 within the same subnet - trying to stay away from 802.1q stuff)... 
>    so I modified each guest's /etc/hosts, etc/sysconfig/network,
>    etc/sysconfig/network-scripts/ifcfg-eth0 and then shutdown both guests. 
>    Then modified the configs on the host and rebooted.
> 
>    When it boots now it seems like it's fine but there is no network
>    connectivity and the default route is pointing to the virbr0 interface!!
>    ifconfig shows eth0 but without an IP address
> 
>    If I do a 'service network restart' then everything works fine again, eth0
>    has the correct IP and the default route is in place.  At that point
>    everything seems fine with the exception of:
> 
>    I get this every two minutes now:
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: warning : Failed to find the network: Is the daemon running ?
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: warning : Failed to find a node driver: Is the libvirtd daemon
>    running ?
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: warning : Failed to find the network: Is the daemon running ?
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: Remote error : unable to connect to
>    '/var/run/libvirt/libvirt-sock': Connection refused
>    libvir: warning : Failed to find a node driver: Is the libvirtd daemon
>    running ?

Tis means the libvirtd isn't running

> 
>    'service libvirtd status' shows:
>    libvirtd dead but subsys locked
> 

And this obviously confirms it.

>    I do notice that when I launch virt-manager there is nothing listed in the
>    'virtual network' tab - it's all greyed out.

Due to libvirtd not running

> 
>    another error I noticed is:
>    virsh net-list --all
>    error: Failed to list active networks
>    error: this function is not supported by the hypervisor:
>    virConnectNumOfNetworks

Again same thing


>    Where am I to fix this weirdness?  Changing IPs shouldn't involve all of
>    this!  Especially when I'm only changing eth0 and they are all in the same
>    subnet as before and nothing else was modified.

Yeah its very odd that this is related. 

At least if you do  'service libvirtd stop' to clear the dead PID file,
and then 'service libvirtd start' it should hopefully be back to normal.
If it still crashes, then best to try running /usr/sbin/libvirtd
manually, or under gdb/valgrind and capture a trace


Once libvirtd is running you can disable virbr0 with

  virsh net-destroy default
  virsh net-autostart --disable default

which will stop 'virbr0' running / being created - its only required if
you want to use NAT, not for bridging

Regards,
Daniel
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