[Beowulf] ntpd wonky?

Gerry Creager gerry.creager at tamu.edu
Tue Feb 17 09:30:49 PST 2009

Greg Lindahl wrote:
> On Thu, Dec 11, 2008 at 11:01:31PM -0800, Bernard Li wrote:
>> Have you tried other pools eg. pool.ntp.org?
> That is stable for me. So it's not me, it's Red Hat's pool that's
> wonky.
> I see that CentOS switched to using ntp.org in 5.2, which I didn't
> automagically get thanks to rpm creating ntpservers.rpmnew, even
> though I hadn't modified the ntpservers file. Mmf.

After a network performance class at the Internet2 Joint Techs meeting 
in early Feb, I ditched the centos/redhat pools, and have a bunch of 
discrete entries in my ntp.conf file.  The entries I'm using are seen below:
server owamp.hous.net.internet2.edu
server owamp.chic.net.internet2.edu
server owamp.atla.net.internet2.edu
server now.okstate.edu
server terrapin.csc.ncsu.edu
server otc1.psu.edu
server time-c.timefreq.bldrdoc.gov
server utcnist.colorado.edu

ntpstat is showing a fairly stable 0.5 ms jitter with a 37 ms offset 
from an IRIG-locked system at owamp.hous.net.internet2.edu

The recommendation from the I2 geeks was to have at least 5 servers of 
known stratum 1 capability.

I'm planning to put my own GPS-timed system into my network to 
accommodate all my clusters.


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