Tuesday, January 6, 2009

Running NTPD inside XEN domU or not?

There is a question how to configure ntpd time synchronization daemon inside Linux domU. Is it better to guarantee the proper time of dom0 via ntpd and rely on automatic time synchronization between domU and dom0? Or is it preferable to make the domU clock independent of dom0?

I'm not sure with the right answer. I'm used to configuring ntpd daemon of each Linux system the same way. That means one configuration is suitable almost for each system. So I would rather use the second way to do it. Before it, you need to tell the system to make the domU clock independent with Linux sysctl interface:
echo "xen.independent_wallclock = 1" >> /etc/sysctl.conf
sysctl -p
After the above action, you can configure ntpd as you wish. For sure, check the set value with
sysctl xen.independent_wallclock

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