[nSLUG] Why is ntp so terrible?

John Weintraub johnweintraub at gmail.com
Fri Mar 10 00:20:32 AST 2017

I agree with billdavidson at eastlink.ca. It really does seem to be more of a
configuration issue (somewhere) than an actual ntpd issue.

Cheers JJW

On Thu, Mar 9, 2017 at 6:20 PM, <billdavidson at eastlink.ca> wrote:

> I work in an enterprise environment with literally tens of thousands of
> Linux hosts, all running ntpd, and all have their clocks synced to within
> milliseconds.  I can directly compare logs on client and server hosts and
> everything agrees.  What are you seeing in NTP logs on your LAN hosts?
> What does ntpq tell you?
> I have certainly seen the effects of clock skew.  A while ago we rolled
> out some new hosts in a DMZ subnet, which is largely isolated from our
> intranet.  They connected to a new dedicated NFS filer, which had a bad NTP
> configuration (actually a missing firewall rule so the filer couldn't
> connect to its NTP master).  As a result the time on the filer eventually
> drifted, which made time stamps on files several minutes in the future,
> which broke our processes which depended on those time stamps.  It was a
> mess.
> On Mar 9, 2017 8:58 PM, D G Teed <donald.teed at gmail.com> wrote:
> So we have a LAN, with one system designated as the ntp server.
> It is set to sync time to a couple of stratum 2 sources.  All other servers
> name the local ntp server on the LAN as the ntp source.  After a few weeks
> we notice the time everywhere is different.  Some are doing OK, others
> are off by quite a few minutes or maybe only 5 minutes.  It doesn't matter
> so much that we have the time synced with the NRC atomic clock,
> but that time within the LAN is tight.  Services like drive mappings
> fail without that feature.
> I feel like we could do better running no daemon on the bulk of the systems
> and simply cron ntpdate (yeah, deprecated - whatever) to run 4 times a day.
> The current ntp performance isn't much worse than not running ntp
> and just relying on the system clock.
> I normally don't do anything special when installing ntpd.  I use
> the default setting in the conf except I customize the server line
> to use my local ntpd.
> Is anyone else feeling ntp is not performing as designed?
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John Weintraub
#333-7451 Moffatt Rd.
Richmond BC Canada
V6Y 3W3
johnweintraub at gmail.com
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