Richard B. Gilbert wrote: > Unruh wrote: >> "Richard B. Gilbert" <[EMAIL PROTECTED]> writes: >> >>> Unruh wrote: >>>> "Richard B. Gilbert" <[EMAIL PROTECTED]> writes: >>>> >>>> >>>>> There are other tools than NTPD. One called "chrony" MAY meet your >>>>> needs, or may not. NTPD is very good at working over the Internet >>>>> with its unpredictable queuing delays. Chrony, as I understand it, >>>>> is not so good at working over the internet. >>>> No idea where you get this from. chrony works over the internet at >>>> least as >>>> well as does ntpd. Its philosophy of dealing with different delays is >>>> different than ntp's( although it can be set up to be virtually >>>> identical) >>>> >>>> >>>>> If you can't keep your machines up 24x7, chrony MAY be a better >>>>> tool. It's possible that you will need something else entirely. >>>> Possibly true. >>>> >>>>> You may find that a hardware reference clock; e.g. a GPS timing >>>>> receiver, will help. With a GPS timing receiver, you will not be >>>>> dependent on the internet for time sources. NTPD will still need >>>>> about thirty minutes to gain really tight synchronization. Once >>>>> gained, synchronization should be stable as long as the machine is up. >>>> Actually it is much worse than that. On my system, on bootup the clock >>>> frequency can very by up to about 50PPM due to a Linux bug. In >>>> general it >>>> takes ntp about 10 hours to regain tight synchronisation. (In that >>>> case it >>>> is microsecond since it is synching to a GPS, but it is also on poll >>>> level >>>> 4 so it has lots of data and should converge faster than some other >>>> system >>>> on poll level 6-10). David Mills has always insisted that ntpd is >>>> designed >>>> for stable long time operation, and rapidity of response is a >>>> distant 49th >>>> or so in priority. >> >>> My Solaris 8 SPARC system seems to be able to synch with the GPS >>> receiver in about 30 minutes. I may reboot that system once a year >> >> IF the frequency after reboot is very close to the frequency before >> (<1PPM >> say) and the clock has not drifter far out ( 1ms say) then sure. >> Otherwise >> it is a disaster.
If I just do a "warm start"; e.g. init 6, with a good drift file, I expect to have tight synchronization very quickly; certainly not more than thirty minutes. If the machine is actually powered down for a while, it may take much longer to achieve tight synchronization. It's not a problem I face very often! I have 202 days uptime at the moment. If we don't have a power outrage, there's no reason for a reboot, we just keep ticking along! _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
