Tuesday, October 26, 2010

Xen's domU always depend on dom0's time and date

By default, the time and date in domU is following dom0. To reset that, below are just what you have to do to decouple the domU's date from dom0

On dom0:

Append xen.independent_wallclock=1 to /etc/sysctl.conf

# echo "xen.independent_wallclock=1"  >> /etc/sysctl.conf
Activate the change
# sysctl -p
Append extra="clocksource=jiffies" to the domU's configuration file.
# echo "extra=\"clocksource=jiffies\"" >> /etc/xen/<domU's name>.cfg 

On domU:

Append xen.independent_wallclock=1
# echo "xen.independent_wallclock=1"  >> /etc/sysctl.conf 
Activate the change
# sysctl -p 
Append jiffies to /sys/devices/system/clocksource/clocksource0/current_clocksource
# echo "jiffies" >> /sys/devices/system/clocksource/clocksource0/current_clocksource

Now you can set your domU's date using "date" command or "ntpdate" to get update from ntp servers.

That's all folks

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