How to fix a broken Xen DomU¶
Some Xen DomU issues we ran into and how we fixed them.
How to fix "clocksource/0: Time went backwards"¶
- Add the following command to /etc/rc.local
echo "jiffies" > /sys/devices/system/clocksource/clocksource0/current_clocksource - See also http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1098
SNMP Monitoring Problems¶
- Were caused by spurious second default routes on DomUs with two DHCP-configured network interfaces.
- See Debian Bug #507452 and RT#32615.
How to fix a broken Xen DomU created with xen-tools 3.9¶
In the Dom0¶
Replace "sda" by "xvda" in the DomU configuration file:
root@phd-xenhost:/etc/xen/ # diff alohomora alohomora2
16c16
< root = '/dev/sda2 ro'
---
> root = '/dev/xvda2 ro'
18,19c18,19
< 'phy:/dev/vg0/alohomora-swap,sda1,w',
< 'phy:/dev/vg0/alohomora-disk,sda2,w',
---
> 'phy:/dev/vg0/alohomora2-swap,xvda1,w',
> 'phy:/dev/vg0/alohomora2-disk,xvda2,w',
In the DomU¶
Replace "sda" by "xvda" in /etc/fstab and "tty1" by "hvc0" in /etc/inittab:
root@phd-xenhost:/mnt/ # diff tmp/etc/inittab tmp2/etc/inittab
54c54
< 1:2345:respawn:/sbin/getty 38400 tty1
---
> 1:2345:respawn:/sbin/getty 38400 hvc0
root@phd-xenhost:/mnt/ # diff tmp/etc/fstab tmp2/etc/fstab
5,6c5,6
< /dev/sda1 none swap sw 0 0
< /dev/sda2 / ext3 noatime,nodiratime,errors=remount-ro 0 1
---
> /dev/xvda1 none swap sw 0 0
> /dev/xvda2 / ext3 noatime,nodiratime,errors=remount-ro 0 1
root@phd-xenhost:/mnt/ #