[CentOS] timekeeping on VM - ntpd running

Thomas Harold thomas-lists at nybeta.com
Mon Nov 30 17:14:13 UTC 2009

On 11/30/2009 11:34 AM, Jonathan Garden wrote:
> This is really stupid question. But referring to:
> http://lists.centos.org/pipermail/centos/2009-October/083791.html
> I don't see any line related to ntpd in my /var/log/messages . Do I need
> to turn-on ntpd for timekeeping on VMs? Some people say not to use ntpd
> on VMs for timekeeping or is it ntpdate cron job? Can someone please
> elaborate on this?

On Xen guests, unless /proc/sys/xen/independent_wallclock is set to 1, 
the DomU will slave itself to the Dom0 clock.  So you probably don't 
need NTP inside the DomU.  Our Dom0 uses ntpd to keep itself 
synchronized with the internal time servers on our LAN.

Whether that is better then using ntpd combined with setting that flag 
to zero... I'm not sure.

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