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[Xen-users] DomU clock out of sync

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] DomU clock out of sync
From: Dmitry Nedospasov <dmitry@xxxxxxxxx>
Date: Sat, 14 May 2011 13:05:36 +0200
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Hey all,

I was watching some logs on a domU today and i suddenly noticed that the
timestamps were off by something on the order of 47 seconds. I was
surprised because *I don't* run independent wall clocks. I checked
some other domUs and the "drift" was also very close to that of the
first domU.

I also checked another dom0, Here the domUs were "only" out of sync by
~11 seconds.

The dom0s are all debian squeeze with Xen 4.0.1-2. The domUs are also
debian squeeze and utilizing PV with the ParaVirtOPs in the normal
debian linux-image-2.6.32 kernel.

I am currently using ntpdate (in cron.hourly) on my dom0s, could this be
the problem? Is there a difference in the way ntpdate updates time the
way ntpd does? IIRC ntpd updates time continuously, correct?

Can someone explain why this would happen. Could this be caused by a
xend restart?

After googling, I'm surprised a best practice solution isn't listed on
XenFaq...  considering how many users seem to be frustrated with this
issue.

All the best,

D.
-- 
Dmitry Nedospasov <dmitry@xxxxxxxxx> -- Twitter: @nedos
Web: http://nedos.net -- Github: http://github.com/nedos

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