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Ubuntu 12.04 and Xen

25-03-2013, 21:58
So i done some digging about and discovered OVH offer XenServer which was more suited for my needs, reinstalled and all is working as expected.

So theres several VMs running Ubuntu 12.04.2. Whenever they are left for ~30 mins with no traffic over ipv6, the network becomes unavailable, requiring the restart of the networking service to bring it back up. IPv4 is still active.

:~# ping6
connect: Network is unreachable
They are able to ping other VMs running on the same Host OS, but nothing above the host, even though the host and other VMs have IPv6 access.

Any help is appreciated. Wader

23-03-2013, 11:36
You should use bridged, unless you specifically assign an IP to a VM. So re-enable the bridge you've commented out.

21-03-2013, 16:20
I managed to get xen working last night by using the vanilla kernel, the same as Felix has suggested, however im having issues with the ip routing now.

I've changed the settings on the host OS of /etc/xen/xend-config.sxp. Commented out the bridging settings and uncommented the routes.


# To bridge network traffic, like this:
# dom0: ----------------- bridge -> real eth0 -> the network
#                            |
# domU: fake eth0 -> vifN.0 -+
# use
#(network-script network-bridge)

#(vif-script vif-bridge)

## Use the following if network traffic is routed, as an alternative to the
# settings for bridged networking given above.
(network-script network-route)
(vif-script     vif-route)

I then added the routes to the guest os as shown here

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
 post-up /sbin/ip route add dev eth0
 post-up /sbin/ip route add default via

 # post-up  ethtool -K eth0 tx off

# The commented out line above will disable TCP checksumming which
# might resolve problems for some users.  It is disabled by default
However the guest OS has no network access and using tcpdump on the host os yields no results. This is how the guest OS fails a ping to the host OS

:~# ping -c 3
PING ( 56(84) bytes of data.
From icmp_seq=1 Destination Host Unreachable
From icmp_seq=2 Destination Host Unreachable
From icmp_seq=3 Destination Host Unreachable

--- ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2000ms
pipe 3

20-03-2013, 13:12
Wader wrote:
> -rwxr-xr-x 1 root root 962 Oct 25 05:40 06_OVHkernel

chmod -x /etc/grub.d/06_OVHkernel

Then retry. the goal of 06_OVHkernel is to put the ovh kernel up top, with
chmod -x you deactivate it.

20-03-2013, 12:36
Silly question but did you update-grub after changing the kernel selection?

20-03-2013, 00:59

I've just ordered a EG 64G HYBRID as my third purchase from ovh.

I've installed xen-hypervisor-amd64, set the GRUB_DEFAULT (in /etc/default/grub) to "Xen 4.1-amd64" and set the TOOLSTACK (in /etc/default/xen) to "xm", however upon rebooting and running the command "xm list" im presented with this error.

ERROR: Can't find hypervisor information in sysfs!

which obviously means xen isnt running. Googling suggests that the kernels could be loading in the wrong order with grub, so i've reordered them in /etc/grub.d/ appropriately, however still to no avail.

/etc/grub.d/ dir.

-rwxr-xr-x   1 root root 6743 Jan 22 14:18 00_header
-rwxr-xr-x   1 root root 5522 Mar 19  2012 05_debian_theme
-rwxr-xr-x   1 root root  962 Oct 25 05:40 06_OVHkernel
-rwxr-xr-x   1 root root 6335 Mar 19  2012 10_linux_xen
-rwxr-xr-x   1 root root 7780 Jan 22 14:18 20_linux
-rwxr-xr-x   1 root root 7603 Apr 17  2012 30_os-prober
-rwxr-xr-x   1 root root 1388 Jan 22 14:18 30_uefi-firmware
-rwxr-xr-x   1 root root  214 Mar 19  2012 40_custom
-rwxr-xr-x   1 root root   95 Mar 19  2012 41_custom