Re: ntpd crashes.

[Camaleón <noelamac@gmail.com>]

El 2012-09-22 a las 12:42 -0700, unruh escribió:

(resending to the list)

> In linux.debian.user, you wrote:

(...)

> >> >> It seems not ntp problem but a kernel bug:
> >> >>
> >> >> http://my.opera.com/marcomarongiu/blog/2010/08/18/debugging-ntp-again-part-4-and-last
> >> >
> >> > You can try the mentioned work-around and see if that works for you.
> >> >
> >> > Anyway, if that's the case, you should experience the same with different
> >> > ntp daemons and not just with ntpd :-?
> >> 
> >> I've experienced the same problem also with openntp.
> >
> > That makes more sense. 
> >
> > Anyway, no NTP daemon should crash because of skewed time; one thing is 
> > that it refushes to sync (which can be fine, and should log this fact 
> > so the admin can make the proper measures) but a different thing is 
> > completely killing the service.
> 
> One of the features of ntpd-- as stated in the documentation-- is that
> if the time is too far out, ntpd will put a warning into the log file
> and exit/quit. If that happens the attitude of Mills is that something
> is very seriously wrong, and the best thing that ntpd can do is to quit,
> and let a human fix theproblem. It does not crash. It quits in an
> orderly fashion. If you want something that does not quit, and does not
> have the 500PPM limit of clock slewing, get chrony.

Yes, thanks for the hints. It seems to be in the end a software design 
restriction which makes not much sense to me. A software delevoper 
should understand that an exited daemon is of no help neither for an 
admin human being nor for an automated system: quitting is the worst a 
process can do and not only because a needed service is stopped but 
also because no logs and no more information will be provided. Nothing.

On the other hand, I guess ntpd can be configured to sync with remote 
servers at predefined interval (i.e., 5 or 12 minutes) that way, 
unless the host clock is badly broken, the time will be kept synced.

> >> Now I'm back with ntp using the workaround mentioned, hope it works.
> >
> > Perfect, tell us how it went.
> 
> IF the clock really does jump suddenly by an hour, it will never work.

Well, I think the work-around is precissely to avoid the kernel from 
going nuts with the time.

Greetings,

-- 
Camaleón