Re: Occasionally high root dispersion shortly after start
Miroslav Lichvar <[email protected]>
| Newsgroups | gmane.comp.time.chrony.user |
|---|---|
| Message-ID | <Y8/+BNJULij2cbl0@localhost> |
On Tue, Jan 24, 2023 at 04:35:48PM +0100, [email protected] wrote: > Note the root dispersion of more than 400 seconds. As a result, some clients > discard NTP responses from this chrony instance for almost 20 minutes. > > Network operations employing our devices have stated they strongly prefer > minimizing NTP traffic and server load, so lowering minpoll is not a viable > option, unfortunately. > > Is this behaviour intentional? If so, is there a configuration option I could > set in chrony.conf to work around the issue? It is expected if you don't have a driftfile. With the iburst option there are 4 measurements made over just ~6 seconds, which gives a huge uncertainty in the measured frequency. If you cannot enable driftfile to avoid wearing out the flash memory, you could generate one on start on tmpfs with a skew matching the maximum expected error of the clocksource, e.g. "0.0 50.0" for 0.0 +/- 50 ppm. This should make the dispersion rate after iburst more reasonable and acceptable for clients. -- Miroslav Lichvar -- To unsubscribe email chrony-users-request-kWFZVVI9zxvPqho9SqqRMmD2FQJk+8+b@public.gmane.org with "unsubscribe" in the subject. For help email chrony-users-request-kWFZVVI9zxvPqho9SqqRMmD2FQJk+8+b@public.gmane.org with "help" in the subject. Trouble? Email [email protected]