[ntp:questions] NTP architecture with virtual machines for stratum-2 ?

janfrode at tanso.net janfrode at tanso.net
Mon Mar 4 21:56:33 UTC 2013


kl. 21:20:46 UTC+1 mandag 4. mars 2013 skrev unruh følgende:


> 
> Virtualisation and time keeping should be kept as far apart as possible.
> 
> Time keeping should be done by the base OS, not by one of the virtual
> 
> ones. Otherwise you will get fights and bad times.


Yes, I know this is common wisdom, but is it still correct ? With linux/KVM we have a paravirtualized clock. Original documentation: https://lkml.org/lkml/2010/4/15/355 and current timekeeping.txt:  http://lxr.linux.no/#linux+v3.8/Documentation/virtual/kvm/timekeeping.txt

Also, won't an ntpd without a LOCAL clock quickly stop serving time if it's out of sync with it's remote time sources?
    


> 
> 
> >
> 
> > Should our stratum-2 servers all be connected to ntp1-4, or is it better to have server1-ntp1, server2-ntp2, etc.. to make sure they don't all run off the same clock source? i.e. should we for server1 have ntp.conf with:
> 
> 
> If source a gives good time, why should you worry about many machines
> using it? 

I don't know, that's why I'm asking :-)
We have had problems with our current stratum-1 device -- I just imagined it might be better in failure situations if all our clients are pointed at stratum2 servers with different reference clocks, than all hanging on the same buggy reference clock .. ?

> 
> 
> And what error budget do you have for the clocks. Do they all have to
> have nanosecond accuracy, or one second accuracy?
> 

No nano second accuracy needed. One second accuracy is probably enough.



   -jf



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