xen vm not keeping date/time properly

George Magklaras georgios at biotek.uio.no
Thu Jan 22 17:49:02 UTC 2009

Ryan Golhar wrote:
> says xen just passed the time-related calls to Dom0, but that 
> can't be the case because the times are different.
That is because if you do run ntpd inside the VM, this can create the 

> noselect?  inside the VM?
Yes on the guest system, and run ntpd normally on the Dom0.

> We are running on a Sun SunFire X4150.
What I stated was on a Dell 2950 PowerEdge, but I shall get hold of a 
SunFire and repeat the test, see if I get the same issue. It does state 
that there might be some kernel parameters that need tweaking, but, I am 
curious to find out what's going on, as we will be using SunFire kit 
with Xen soon.


> George Magklaras wrote:
>> This page might offer some help:
>> http://support.ntp.org/bin/view/Support/KnownOsIssues#Section_9.2.2.
>> To recap, we use the 'noselect' keyword to avoid the running ntpd on 
>> the client to attempt to sync with the defined servers and ntpq does 
>> not report any disturbing drifts on the client...and we do run ntpd 
>> normally (no 'noselect') on Dom0.
>> What happens (happened if you have already tried) if you try and do 
>> this? And what's your hardware platform?
>> GM

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